Add memory project/path consistency: doctor check + shared-replace guard

[Kashkovsky]

Summary

Recall scopes and boosts by the project segment in a memory's storage path, so a memory whose frontmatter project disagrees with that path ranks under the wrong project (or misses a project-scoped pass). Item 8 from the recall relevancy audit: prevent the drift at its source and detect any that already exists.

Detail

Root cause of the drift: storeSharedMemoryReplacement updates a shared memory in place at its existing targetUri but built the frontmatter from options.metadata.project ?? inferred.project — so a caller passing a different project produced a file that stays under the old path while its frontmatter claims the new project. That is exactly how .../shared/docs-desktop/durable/projects/coda/docs-desktop-pagerduty-onboarding.md ended up tagged project: mobile-native.

• storeSharedMemoryReplacement now takes project/topic from the storage path (inferred wins over a differing caller value) and warns, since the file stays put. Changing a shared memory's project means relocating it (forget + store anew), not editing frontmatter at the old path.
• New memory project consistency doctor check walks the on-disk memories tree and reports any memory whose frontmatter project differs from its path project segment. Read-only. Compares via uriSegment so case/slug normalization is not a false positive; skips project-less kinds (preferences, smoke), absent-project memories (the general default), directory nodes, and summary sidecars.
• New pure helpers in utils.ts: memoryUriProjectSegment (de-scopes shared team paths, handles durable/handoffs/incidents) and memoryFrontmatterField.

Test plan

npm run test        # 315 pass (25 files); +10 covering the URI/frontmatter
                    # helpers, the shared-replace path-wins guard + warning,
                    # and the doctor check (clean / drift / no-dir cases)
npm run typecheck   # clean (root + test/tsconfig.json)
npm run lint        # clean

Ran threadnote doctor against the live corpus — the check found exactly the one real divergence and nothing else:

WARN memory project consistency: 1 memory(ies) whose frontmatter project differs
from their storage path; re-store under the correct project to fix:
.../shared/docs-desktop/durable/projects/coda/docs-desktop-pagerduty-onboarding.md
(frontmatter "mobile-native" vs path "coda")