fix(extensions): update provides.hooks in 7 extension manifests to match actual registrations (#3157)
Audit found that 7 bundled extensions had incomplete provides.hooks
arrays in their manifests. Updated each to match actual pi.on() calls:
- async-jobs: +session_before_switch, session_shutdown
- bg-shell: +8 hooks (session_compact, session_tree, etc.)
- browser-tools: +session_start
- context7: +session_shutdown
- google-search: +session_shutdown
- gsd: +12 hooks (bash_transform, tool_call, tool_result, etc.)
- search-the-web: +session_start
Closes #3156
f0059a5498