Merge branch 'worktree-agent-a63474e92b05425a5'

# Conflicts:
#	Cargo.lock
#	Cargo.toml

tickets/012-metrics-ui.md

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+# 012 — Metrics UI
+
+## Summary
+
+Replace the current "Coming Soon" Metrics placeholder with a real component: declare
+metrics via the metric language, and view their derived values.
+
+## Scope
+
+- A form/editor for declaring a metric (regex + param matchers) that calls
+  `POST /api/metrics` ([004](004-metrics-api.md)), with inline validation errors
+  surfaced from the API's 4xx responses.
+- List of currently-declared metrics with their labels.
+- A view of a selected metric's bucket values over the active time range (reuse the
+  time-range plumbing already in `App.tsx`/`LogTimeline`).
+
+## Acceptance criteria
+
+- Declaring a metric in the UI immediately reflects newly-matching logs (existing
+  and new) in the metric's value view, per the backfill behavior from
+  [003](003-metric-bucket-derivation.md).
+- Invalid metric definitions show the backend's validation error instead of failing
+  silently.
+
+## Depends on
+
+- [004 — Metrics API](004-metrics-api.md)