feat(scale): implement scale auto with persistent rules

[wjgong001]

Closes #226

Implements sh1pt scale auto with:

• Persistent auto-scaling rules stored in ~/.sh1pt/auto-scale-rules.json
• --min <n>, --max <n>, --target-cpu <%>, --cooldown <s> options
• --enable / --disable to toggle
• --show to display current rules
• Input validation with clear error messages

Also enhanced:

• sh1pt scale cost — shows provider pricing reference table when no fleet is detected
• sh1pt scale status — now shows auto-scaling rule state

Type-checked with tsc --noEmit — zero errors.

[github-actions]

🤖 Auto-rebase: The branch was rebased successfully locally but could not be pushed to the fork. Please enable 'Allow edits from maintainers' in the PR settings, or rebase manually: git fetch upstream master && git rebase upstream/master.

[github-actions]

🤖 Auto-rebase: The branch was rebased successfully locally but could not be pushed to the fork. Please enable 'Allow edits from maintainers' in the PR settings, or rebase manually: git fetch upstream master && git rebase upstream/master.

[github-actions]

🤖 Auto-rebase: The branch was rebased successfully locally but could not be pushed to the fork. Please enable 'Allow edits from maintainers' in the PR settings, or rebase manually: git fetch upstream master && git rebase upstream/master.

[github-actions]

🤖 Auto-rebase: The branch was rebased successfully locally but could not be pushed to the fork. Please enable 'Allow edits from maintainers' in the PR settings, or rebase manually: git fetch upstream master && git rebase upstream/master.