Add code of conduct and issue templates

.github/CODE_OF_CONDUCT.md

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+# Contributor Covenant Code of Conduct
+
+## Our Pledge
+
+We as members, contributors, and leaders pledge to make participation in our
+community a harassment-free experience for everyone. We pledge to act and
+interact in ways that contribute to a healthy community.
+
+## Our Standards
+
+Examples of behavior that contributes to a positive environment for our
+community include:
+
+* Demonstrating empathy and kindness toward other people
+* Being respectful of differing opinions, experiences, and each other's time
+* Giving and gracefully accepting constructive feedback
+* Accepting responsibility and apologizing to those affected by our mistakes,
+  and learning from the experience
+* Focusing on what is best not just for us as individuals, but for the overall
+  community
+
+Examples of unacceptable behavior include:
+
+* The use of sexualized language or imagery, and sexual attention or advances of
+  any kind
+* Trolling, insulting or derogatory comments, and personal or political attacks
+* Public or private harassment
+* Publishing others' private information, such as a physical or email address,
+  without their explicit permission
+* Spam posts or excessive self-promotion
+* Other conduct which could reasonably be considered inappropriate in a
+  professional setting
+
+## AI Policy
+
+Using LLMs to assist in writing, translation, and software development is fine,
+as long as the final output - whether that be code or text - is correct and up
+to standards.
+
+Please do not submit PRs largely based on "AI slop" code. If you cannot explain
+an implementation without going back to the LLM, do not submit it. Maintainer
+time is scarce, and we ask that you respect that by not forcing maintainers to
+be the human-reviewer-in-the-loop for a code generation tool. In any case,
+non-trivial code generation tool use must be disclosed in the PR.
+
+Issues and PRs that look like unreviewed LLM output will be closed without
+detailed feedback, and constitute a violation of this Code of Conduct.
+
+## Enforcement Responsibilities
+
+Community leaders are responsible for clarifying and enforcing our standards of
+acceptable behavior and will take appropriate and fair corrective action in
+response to any behavior that they deem inappropriate, threatening, offensive,
+or harmful.
+
+Community leaders have the right and responsibility to remove, edit, or reject
+comments, commits, code, wiki edits, issues, and other contributions that are
+not aligned to this Code of Conduct, and will communicate reasons for moderation
+decisions when appropriate.
+
+## Scope
+
+This Code of Conduct applies within all community spaces, and also applies when
+an individual is officially representing the community in public spaces.
+Examples of representing our community include using an official e-mail address,
+posting via an official social media account, or acting as an appointed
+representative at an online or offline event.
+
+## Enforcement
+
+Instances of abusive, harassing, or otherwise unacceptable behavior may be
+reported to the community leaders responsible for enforcement at
+[berend.markhorst@gmail.com](mailto:berend.markhorst@gmail.com).
+All complaints will be reviewed and investigated promptly and fairly.
+
+All community leaders are obligated to respect the privacy and security of the
+reporter of any incident.
+
+## Enforcement Guidelines
+
+Community leaders will follow these Community Impact Guidelines in determining
+the consequences for any action they deem in violation of this Code of Conduct:
+
+### 1. Correction
+
+**Community Impact**: Use of inappropriate language or other behavior deemed
+unprofessional or unwelcome in the community.
+
+**Consequence**: A private, written warning from community leaders, providing
+clarity around the nature of the violation and an explanation of why the
+behavior was inappropriate. A public apology may be requested.
+
+### 2. Warning
+
+**Community Impact**: A violation through a single incident or series of
+actions.
+
+**Consequence**: A warning with consequences for continued behavior. No
+interaction with the people involved, including unsolicited interaction with
+those enforcing the Code of Conduct, for a specified period of time. This
+includes avoiding interactions in community spaces as well as external channels
+like social media. Violating these terms may lead to a temporary or permanent
+ban.
+
+### 3. Temporary Ban
+
+**Community Impact**: A serious violation of community standards, including
+sustained inappropriate behavior.
+
+**Consequence**: A temporary ban from any sort of interaction or public
+communication with the community for a specified period of time. No public or
+private interaction with the people involved, including unsolicited interaction
+with those enforcing the Code of Conduct, is allowed during this period.
+Violating these terms may lead to a permanent ban.
+
+### 4. Permanent Ban
+
+**Community Impact**: Demonstrating a pattern of violation of community
+standards, including sustained inappropriate behavior, harassment of an
+individual, or aggression toward or disparagement of classes of individuals.
+
+**Consequence**: A permanent ban from any sort of public interaction within the
+community.
+
+## Attribution
+
+This Code of Conduct is adapted from the [Contributor Covenant][homepage],
+version 2.1, available at
+[https://www.contributor-covenant.org/version/2/1/code_of_conduct.html][v2.1].
+
+Community Impact Guidelines were inspired by
+[Mozilla's code of conduct enforcement ladder][Mozilla CoC].
+
+For answers to common questions about this code of conduct, see the FAQ at
+[https://www.contributor-covenant.org/faq][FAQ]. Translations are available at
+[https://www.contributor-covenant.org/translations][translations].
+
+[homepage]: https://www.contributor-covenant.org
+[v2.1]: https://www.contributor-covenant.org/version/2/1/code_of_conduct.html
+[Mozilla CoC]: https://github.com/mozilla/diversity
+[FAQ]: https://www.contributor-covenant.org/faq
+[translations]: https://www.contributor-covenant.org/translations

.github/ISSUE_TEMPLATE/BUG_REPORT.md

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+---
+name: Bug report
+about: Create a bug report highlighting an issue.
+title: ''
+labels: ''
+assignees: ''
+---
+
+#### Describe the bug
+
+[ A clear and concise description of what the bug is.
+This should explain **why** the current behaviour is a problem and why the expected output is a better solution. ]
+
+#### Code sample
+
+```python
+# Your code here that produces the bug
+# This example should be self-contained, and so not rely on external data.
+# It should run in a fresh Python session, and so include all relevant imports.
+```
+
+<details>
+
+**Note**: Please be sure you are using the latest released version of `steinerpy`, or a recent build of `main`.
+If your problem has been fixed in an unreleased version, you might be able to use `main` until a new release occurs.
+
+**Note**: If you are using a released version, have you verified that the bug exists in the `main` branch of this repository?
+
+</details>
+
+If the issue has not been resolved, please file it in the issue tracker.
+Make sure to include the version of Python you are using, and the version of `steinerpy` you run.
+You can copy-paste the output of `import steinerpy, sys; print(steinerpy.__version__, sys.version)` to achieve this.
+
+#### Expected Output
+
+A clear and concise description of what you expected to happen.

.github/ISSUE_TEMPLATE/FEATURE_REQUEST.md

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+---
+name: Feature request
+about: Suggest an idea for this project.
+title: ''
+labels: ''
+assignees: ''
+---
+
+#### Is your feature request related to a problem? Please describe
+A clear and concise description of what the problem is.
+For example, start with "I'm always frustrated when [...]", and go from there.
+
+#### Describe the solution you'd like
+A clear and concise description of what you want to happen.
+
+#### Describe alternatives you have considered
+A clear and concise description of any alternative solutions or features you have considered.
+
+#### Additional context
+Add any other context about the feature request here.

CONTRIBUTING.md

@@ -3,6 +3,12 @@
 Thank you for considering contributing to SteinerPy! We welcome bug reports,
 feature requests, documentation improvements, and pull requests.
 
+## Code of Conduct
+
+Participation in this project is governed by our
+[Code of Conduct](.github/CODE_OF_CONDUCT.md). Please read it before opening an
+issue or pull request.
+
 ## Before you start
 
 Conversations about new features and non-trivial changes belong in the