dot add module + conflict resolution

[mathieusouflis]

Problem statement

There is no way to safely add a module (Postgres, Redis, Docker) to a project after dot init. The conflict detection infrastructure (manifest hash comparison, conflict markers) exists in design but is not implemented.

Proposed solution

Implement the full dot add module flow with conflict detection:

1. dot add module <name> — run generator Apply(), pipe through conflict-aware pipeline
2. Conflict detection — compare current file hash to .dot/manifest.json
3. Conflict marker writing — git-style markers for modified files
4. dot status — list files with unresolved conflicts
5. dot resolve — mark resolved, update manifest hashes

Alternatives considered

No response

Area

Core

Additional context

Children:

• [Decision] Conflict marker format + dot resolve UX (open-decisions.md 2)
• dot add module command
• Conflict detection (manifest hash comparison)
• Conflict marker writing
• dot status command
• dot resolve command
• Edge case tests (binary files, deleted files, renamed files)