feat(tui): Phase 2 dynamic metrics — compaction/STT models, inference params, test coverage

[bug-ops]

Context

PR #2159 implemented Phase 1 TUI dynamic metrics. Phase 2 items were deferred due to cross-crate complexity or lower priority.

Tasks

Cross-crate model fields

• stt_model: Option<String> — STT model name; requires plumbing through zeph-channels or a dedicated config accessor
• compaction_model: Option<String> — summarization/compaction model; lives in llm.summary_model config but not currently exposed in MetricsSnapshot

Inference parameter display

• provider_temperature: Option<f32> — current temperature for active provider
• provider_top_p: Option<f32> — current top_p for active provider
• These are runtime-dynamic (can change on /provider switch) so require watch channel update, not just startup population

Naming fix

• Rename cache_enabled → semantic_cache_enabled in MetricsSnapshot to distinguish from response cache (response_cache_enabled)

Test coverage gaps (identified by tester in PR #2159)

• default_metrics_snapshot test: assert new Phase 1 fields default to zero/empty/false
• MetricsCollector::update round-trip test for new fields
• Resources panel collapsed mode: assert ch: (active_channel) segment visible
• Resources panel: token_budget Some + compaction_threshold None branch
• Resources panel: individual flag rendering (self_learning_enabled alone)
• Resources panel: embedding_model conditional (non-empty) display
• Status bar: model_name non-empty shows inline model segment

Active channel detection improvement

• Replace telegram-token-presence proxy in runner.rs with explicit AnyChannel variant passed to MetricsSnapshot — more robust and accurate

Resources panel

• Decide whether filter confidence line should appear in the Resources panel (dropped in Phase 1 refactor — N3 from reviewer)

References

• PR feat(tui): Phase 1 dynamic metrics — model info, session config, infra status #2159 — Phase 1 implementation
• .local/handoff/reviewer-tui-metrics.md — N1–N4 non-blocking items
• .local/handoff/tester-tui-metrics.md — full test gap list (if preserved)