docs: drop per-release audit notes + legacy spec, scrub phase markers

- /docs/audit/ moved out of the public docs surface (23 per-release
  forensic notes). They were linked from the README but read as
  internal traceability artefacts, not user-facing documentation.
  Kept local for cross-release lookup; added to .gitignore so new
  ones don't re-track.
- /docs/api/openapi-v1422-legacy.yaml removed — superseded by the
  current openapi.yaml on the v1.5 line.
- /docs/api/openapi.yaml info.version bumped 1.4.23 → 1.5.0 so the
  spec matches package.json (the doc claims the version is mirrored
  from the package; previously the mirror had drifted six versions).
- /docs/ops/deploy.md: image name corrected from
  `ghcr.io/marc-bombeck/healthlog` → `ghcr.io/mbombeck/healthlog`
  (the previous command would have 404'd at GHCR); release-process
  framing dropped from a release-pair note.
- /docs/ops/backup-restore.md + /docs/self-hosting/scaling.md:
  trailing phase tags (`v1.4 G1`, `v1.4 G3`, `v1.4.40 W-POOL`)
  stripped from section headers + body. Replaced an internal-notes
  pointer with a concrete `getPoolMax()` reference.

The README pointer to /docs/audit/ is removed in the next commit
along with the rest of the README accuracy pass.

docs/api/openapi.yaml

@@ -1,7 +1,7 @@
 openapi: 3.1.0
 info:
   title: HealthLog API
-  version: 1.4.23
+  version: 1.5.0
   description: >-
     Self-hosted personal-health-tracking PWA — public API surface for the iOS native client and external ingest.