[P1] Stub Cleanup: Remove commands/missing/ directory

[Delqhi]

Task

Remove the 11 .md stub spec files from commands/missing/.

Files to remove

ultraplan.md, bughunter.md, doctor.md, insights.md, btw.md, passes.md, rewind.md, stickers.md, teleport.md, thinkback.md, good-claude.md

Why

These are doc specs — real TypeScript implementations exist in commands_v2/ and packages/opensin-sdk/src/core/commands/. Keeping stubs causes confusion.

Validation

ls commands/missing/ = does not exist

Linked Epic

Epic #1089

[Delqhi]

Complete: Removed 11 command stubs from commands/missing/. Commit 7f232a3. Real implementations exist in commands_v2/ and core/commands/.

[github-actions]

This issue has been automatically locked since it was closed and has not had any activity for 7 days. If you're experiencing a similar issue, please file a new issue and reference this one if it's relevant.