feat(session-query): ship full-text session search opt-in via openAt never

The shipped bundles keep ctx.sessionQuery mounted but set the new
session-query-sqlite `openAt: never` phase: searchSessions/searchEvents
fail with the typed SESSION_QUERY_SEARCH_DISABLED code before any request
normalization, node:sqlite is never imported or opened, and no source
observation or reconciliation runs. Every inherited exact read, filter,
and trace — session export descendants, subagent-fork Workspace
inheritance, title reads — keeps working, and the Web sidebar search
degrades to its designed local title/workspace matching. Enabling content
search is a one-line openAt override in a later patch layer; the web e2e
scaffold keeps it enabled as the assembled opt-in coverage.

packages/session-query/session-query-sqlite/README.i18n.yaml

@@ -2,5 +2,5 @@
 # side as of the last confirmed-consistent state. Both languages carry equal authority;
 # after editing either side, bring the other along and re-record with:
 #   pnpm run verify-translation-pairing --write packages/session-query/session-query-sqlite/README.md
-README.md: 846f79bd8383a8114a6d1329e7dbe931a67d98d0
-README.zh.md: e84e521dd5f392dbcede1e1dd957e4ce0a9bc50f
+README.md: 25257ddbe672d47faf39e1472a1bd882205d8c4e
+README.zh.md: 584e466a5042334e22797a6c2794cce910844d5a