[pitill0]

Summary

Implement opt-in station discovery across Radio Browser and the active local profile through the shared SearchService.

Changes

• Add radio-browser, local, and all search scopes while preserving Radio Browser as the default.
• Require an explicit SQLite connection and profile ID for local and combined searches.
• Merge and deduplicate stations using stream URL identity.
• Preserve profile-specific local metadata and expose temporary source observations separately from station data.
• Apply deterministic relevance ranking, codec compatibility filtering, and a bounded candidate window.
• Report remote search outcomes, distinguishing successful, partial, failed, cached, and unqueried searches.
• Prevent complete Radio Browser request failures from being cached as valid empty results.

Scope

No GTK, TUI, Web UI, Brynse, or SQLite schema changes. UI source selection and persistent station provenance remain separate follow-up issues.

Validation

• make gate — PASS
• 1,580 tests passed, 7 optional Brynse contract tests skipped.
• Ruff, mypy, JavaScript validation, pip-audit, and Bandit passed.

Closes #274