v0.4.0

Replaces the app's custom session store with a port of pi's SessionManager: JSONL persistence, recovery, conversation trees, and compaction now follow pi's semantics, with pi's session-manager test suite ported to Kotlin.

The transcript is now rendered directly from runtime messages instead of mirrored DTOs: tool executions render as one row per call, like pi, and the streaming row survives the persistence write.

Smaller changes: OAuth login for sole-OAuth providers starts straight from the provider row, session search filters refreshed summaries, and search results drop provenance narration.