feat(idb): add IDB content version check system, wire to journals

Adds check_and_clear_idb_tables() helper in core__idb_dexie.ts that clears
Dexie tables when their content version changes. Version numbers live in
IDB_CONTENT_VERSIONS (store_versions.ts); state tracked in localStorage
(ae_idb_ver__{module}__{table}) so each table clears exactly once per bump.

Wired into db_journals.ts (pilot): journal_entry at v3 clears stale
content_md_html/history_md_html data cached before the properties_to_save fix.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

documentation/TODO__Agents.md

@@ -115,6 +115,34 @@ reactivity — only effects that actually read a changed field re-run.
 
 ---
 
+### [Stores] IDB Content Version System (post June 10)
+Scaffold added to `store_versions.ts` (`IDB_CONTENT_VERSIONS` constant) — values defined but
+**not yet wired**. The mechanism mirrors `AE_LOC_VERSION` but targets Dexie table contents
+rather than localStorage keys.
+
+**Why:** `db_save_ae_obj_li__ae_obj` uses a `properties_to_save` whitelist. When that whitelist
+changes (e.g. adding/removing a stored field), existing cached IDB records are stale but never
+automatically cleared. Users see the old shape until a record is individually refreshed.
+
+**How it will work:**
+- Each `db_*.ts` calls a helper (`core__idb_dexie.ts`) on open that checks a `_meta` IDB table
+- If stored version ≠ `IDB_CONTENT_VERSIONS[module][table]`, clear the table + update `_meta`
+- SWR repopulates from API on next access (same as any cold-start)
+- Bump a table's version in `IDB_CONTENT_VERSIONS` when `properties_to_save` changes shape
+
+**IDAA consideration:**
+IDAA tables are already cleared by `indexedDB.deleteDatabase()` on sign-out/auth failure in
+`(idaa)/+layout.svelte`. The content version check is a *complementary* deploy-time reset, not
+a replacement. When wiring IDAA tables, ensure: (a) the check only runs on IDB open, not
+mid-session; (b) the `_meta` table is included in the `deleteDatabase()` wipe scope.
+
+**Tasks:**
+- [x] Write `check_and_clear_idb_tables()` helper in `core__idb_dexie.ts` (2026-05-14)
+- [x] Wire helper into `db_journals.ts` (pilot — `journal_entry: 2` clears stale content_md_html on first load) (2026-05-14)
+- [ ] Roll out to `db_events.ts`, `db_core.ts`
+- [ ] Roll out to IDAA modules (`db_posts.ts`, `db_archives.ts`) — verify auth-wipe interaction first
+- [ ] Update `store_versions.ts` comment from "NOT YET ACTIVE" to document the active mechanism
+
 ### [Stores] Refactor — Phase 2c (deferred)
 Phases 1, 2a, 2b are complete (see ✅ Completed below). One phase remaining: