User story: Search across all content sources

**As a** listener, **I want** to search one query and get results from all my installed plugins, **so that** I don't need to search each source separately.

User story: Search across all content sources

As a listener,
I want to search one query and get results from all my installed plugins,
so that I don’t need to search each source separately.

Priority

Must

Acceptance criteria

1. Given two plugins with search capability are registered, when I type a query in the search bar, then results from both plugins appear.
2. Given one plugin is slow or unresponsive, when I search, then results from responsive plugins appear immediately and the slow plugin’s results arrive when ready (or timeout with a notification).
3. Given two plugins return the same track, when search results are displayed, then the duplicate is merged into one entry.
4. Given no plugins are installed, when I search, then I see a helpful message explaining how to add a plugin.

Notes / constraints

• Search is parallel with per-plugin timeout (FR-CORE-4).
• Deduplication is advisory — may not catch all edge cases (constraint A6).

Traceability

• Requirement IDs: FR-CORE-4, FR-PLUGIN-4
• NFRs: NFR-PERF-4
• Feature docs: docs/user/features/search.md