Restore shared constitution article installation

[darlingm]

Summary

• Port the shared constitution installer omitted from the Babashka launcher.
• Install missing shared articles in the project before configuration is parsed.
• Install missing project and shared articles in role worktrees during runtime synchronization.
• Preserve the original no-overwrite behavior and source ordering.
• Add regression coverage for the project and role-worktree paths.

This behavior was added to the shell launcher in 27b7e83. The function and both call sites disappeared during the larger Babashka port in 9afcb6f, while the pack bootstrap and README continued to expect it.

Fixes #32.

Test plan

• bb test — 25 tests, 97 assertions, 0 failures, 0 errors

[sbernholtz]

hi @unclebob,
+1 on the issue and suggested fix

also, thanks for sharing the swarm forge "agentic orchestration platform", very valuable insights!

[sbernholtz]

I independently reproduced this with the six-pack configuration reduced to one specifier agent.

After running ./swarm:

• swarmforge/scripts/shared-articles/ contained engineering.prompt, handoffs.prompt, and workflow.prompt.
• swarmforge/constitution/articles/ still contained only the three local articles.
• Startup otherwise completed successfully, including the tmux session, handoff daemon, and runtime state.

The live agent initially read only constitution/articles/*.prompt. It discovered shared-articles/handoffs.prompt later only because specifier.prompt mentioned the undefined “file-based handoff format” and the agent
searched for its definition. It then read the remaining shared articles voluntarily.

The agent explicitly confirmed:

The constitution explicitly required only constitution/articles/; it did not include every shared article.

This means the defect can be masked by incidental model exploration, but shared instructions are not reliably loaded. PR #33 restores the documented deterministic behavior.