fix(glob): extract directory prefix from pattern for ripgrep compatibility

Ripgrep's --glob flag silently returns no results when the pattern
contains a directory prefix (e.g. 'apps/backend/**/*.ts'). Models
naturally write patterns this way when exploring unfamiliar codebases.

Extract the static directory segments from the pattern, append them to
the search path, and pass only the glob portion to ripgrep.

src/features/background-agent/manager.ts

@@ -1161,7 +1161,6 @@ export class BackgroundManager {
         properties: props as Record<string, unknown>,
         findBySession: (id) => this.findBySession(id),
         idleDeferralTimers: this.idleDeferralTimers,
-        recentlyCompactedSessions: this.recentlyCompactedSessions,
         validateSessionHasOutput: (id) => this.validateSessionHasOutput(id),
         checkSessionTodos: (id) => this.checkSessionTodos(id),
         nudgeCouncilMemberIfNeeded: (task, sid) => this.nudgeCouncilMemberIfNeeded(task, sid),