[WIP] Downgrade SQLite engine to 2026-05-12 build (012a04ed) to isolate OOM regression

[chiragsalian]

Explanation of Change

• Reverts the SQLite amalgamation (libstuff/sqlite3.c, libstuff/sqlite3.h, libstuff/sqlite3ext.h) from the current build 45f6fccc (2026-07-09) back to 012a04ed (2026-05-12), taken from commit c6d195fd ("new sqlite version from dan"). Code taken from the before this June 5th PR.
• SQLITE_VERSION is unchanged (3.54.0) — only the hctree/engine build (SOURCE_ID) changes. No other files touched.

Why

• The monthly "Account Manager Retention Report" — a large read-only SELECT run via readdb/CustomQuery, doing ~12,763 full-table scans under BEGIN CONCURRENT — has run for ~3 years and now aborts with out-of-memory: {SQLITE} Code: 7, Message: statement aborts at ...: out of memory → 402 Bad query.
• Fleet-wide CustomQuery out-of-memory events were 0 through June, onset 2026-07-06. App-side Bedrock changes in the window were cleared (logging / rate-limiting / write-path locking). The only memory-relevant change underneath this path is the SQLite/hctree engine, which was bumped 3× between the report's last success (012a04ed, May 12) and failure (69941fdc, Jun 17).
• 012a04ed is the last engine build the report ran on cleanly, so this reverts to it.

Tests

• Deploy this branch to a single non-critical follower (not leader / secondary-leader).
• Re-run the report query on that node.
• OOM disappears → confirms the engine bump is the cause. OOM persists → engine is exonerated; look elsewhere.

Caveat

• The amalgamation is reverted ~2 months while keeping current Bedrock C++. Watch CI for any compile incompatibility.