v0.46.1 — fix migration 029 for the §22.13 re-stamp aftermath (OHM deploy fault)

Deploying the three-tier series onto OHM crash-looped on migration 029:
`NOT NULL constraint failed: cached_branches__new.collection_id`, then a UNIQUE
collision. Root cause: the v0.39.0 default→ohm re-stamp updated
cached_rfcs.project_id but NOT the entry-satellite tables, so ~1.3k
cached_branches rows were stranded at project_id='default' — which 029's
per-project collection backfill can't map (NULL), some of which also duplicate
freshly-re-mirrored 'ohm' rows (UNIQUE), and some of which reference entries
that no longer exist.

Fix — a repair prologue at the top of 029 (no schema change):
- drop stale rows that duplicate an already-correctly-stamped row (keep the
  fresh copy) for the branch-keyed tables;
- re-derive each satellite's project_id from its entry (cached_rfcs, by slug);
- drop rows whose entry no longer exists (stale cache, rebuildable from gitea).
A no-op on clean/fresh deployments (empty or consistent satellites).

Validated against a snapshot of the live OHM DB: 029→032 apply cleanly, zero
NULL collection_id, FK check clean, watches/RFCs/branch_visibility preserved,
cached_branches 1397 → 1291 (−67 no-RFC, −39 dups). Fresh-install path
unchanged: existing 029 suite green + a new regression test for the
stale/dup/orphan shape. Full backend suite 547 passed.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

frontend/package.json

@@ -1,7 +1,7 @@
 {
   "name": "rfc-app-frontend",
   "private": true,
-  "version": "0.46.0",
+  "version": "0.46.1",
   "type": "module",
   "scripts": {
     "dev": "vite",