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.

apps/web/tests/scaffold.ts

@@ -391,6 +391,10 @@ export async function launchWebScaffold(options: LaunchOptions = {}): Promise<We
       },
     },
     { id: 'session-persistence-jsonl', config: { root: persistenceRoot } },
+    // Content search is enabled here although the shipped bundles default it
+    // off (`openAt: never`, pinned by apps/cli/tests/lazy-search-startup):
+    // the seeded-session scenarios navigate by content search, and these e2e
+    // runs are the assembled coverage for the opt-in search path.
     { id: 'session-query-sqlite', config: { path: ':memory:', openAt: 'first-search' } },
     // storage-json's yml root is anchored to the real $DSH_HOME; pin the row
     // to an absolute temp root (removed with the workspace at close) so tests