Follow-up on top of the cherry-picked contributor commit for #16751:
1. Delete triggers: the original PR switched FTS5 from external to inline
content mode and concatenated content || tool_name || tool_calls in
the insert/update triggers, but left the delete triggers passing
old.content to the FTS5 delete-command. FTS5 inline delete requires
the content to match what was stored, so every DELETE on messages
raised 'SQL logic error'. Replaced with plain DELETE FROM ... WHERE
rowid = old.id on all four delete paths (normal + trigram, delete +
update-delete).
2. v11 migration: existing DBs have the old external-content FTS tables
and triggers. Because CREATE VIRTUAL TABLE IF NOT EXISTS / CREATE
TRIGGER IF NOT EXISTS skip when the objects already exist, upgraders
would have kept the broken behavior forever. Bumped SCHEMA_VERSION
to 11 and added a migration that drops both FTS tables + all 6 old
triggers, recreates them via FTS_SQL / FTS_TRIGRAM_SQL, and backfills
from messages using the same concatenation expression.
3. Regression tests: 6 new tests cover INSERT / UPDATE / DELETE paths
for tool_name + tool_calls indexing plus the full v10 -> v11 upgrade
path on a hand-built legacy DB.
8d76d69d48