fix: make IdeaLoom list deletion actually delete, and pin its federation boundary

[atomantic]

Summary

• Fixes a real bug: DELETE /api/brain/ideas/idealoom/lists/:id answered 404 for every list, so the Brain IdeaLoom UI could never delete one — it toasted "Failed to delete IdeaLoom list" and left the row in place. deleteList returned store.deleteOne(id), which resolves to undefined whether or not the record existed. It now probes for the record inside the same per-id write queue as the removal and returns a real boolean.

• Adds the CRUD coverage Add machine-local IdeaLoom list storage and validated local API #5336 implied but never wrote — read-by-id, delete, the idempotent second delete, the malformed-id guards on all three id-addressed operations, and both 404 shapes at the route. That gap is exactly why the delete bug shipped.

• Adds server/services/idealoomLists.boundary.test.js, the missing proof that no IdeaLoom list payload or vault sync metadata crosses the Brain federation seam (ADR docs/decisions/2026-08-08-privacy-records-machine-local.md). It drives the real modules over a temp data root rather than asserting on mock calls:

  • the reconcile snapshot carries a native Brain idea but none of the list's id/prompt/note path;
  • getBrainChecksum() is byte-identical across list create/update/settings writes, with a forced cache invalidation plus a native-write bypass probe so it cannot pass vacuously;
  • brainSync.applyRemoteChanges and brainReconcile.applyBrainSnapshot both refuse an idealoom-lists payload and write nothing to the store;
  • the memory bridge has no mapping for the type, so brainRecordToMemory cannot bridge a list.

  Today those guarantees hold only structurally — nothing fails if a later slice registers an IdeaLoom type in BRAIN_ENTITY_TYPES or the bridge's TYPE_MAP. Add explicit opt-in IdeaLoom Obsidian import and export #5338/Make IdeaLoom Obsidian sync conflict-safe and document its contract #5339 are about to hang vault paths and note content hashes off these records, so the boundary needed a test rather than a comment.

Unrelated fix rolled in

The first commit regenerates server/lib/apiRouteCatalog.generated.json. b9893531c added image-generation routes without re-running npm run generate:api-docs, so scripts/generate-api-route-catalog.test.js has been failing on main since — it would have reddened this PR's CI. Regenerated by the script; no hand edits.

Test plan

• cd server && npx vitest run services/idealoomLists.test.js services/idealoomLists.boundary.test.js routes/brain.test.js — 125 passed.
• Bug confirmed: reverting only the deleteList change fails the new deletes a list and reports whether anything was removed test with expected undefined to be true.
• Non-vacuity confirmed: each federation-refusal test seeds a real list first and asserts a non-empty store before the refusal, and each passes when run in isolation.
• cd server && npm test — full suite green (the two pre-existing route-catalog failures are resolved by the first commit).

Closes #5361