activity-stats: shared StatRow + canonical metrics across surfaces

Implements the activity-stats change (specs/activity-stats):

- gpx: `movingTime(tracks)` — moving seconds from trackpoint timestamps,
  excluding stationary spans + long gaps; null when no timestamps.
- stats.ts: pure formatters (distance/elevation/duration/speed/pace),
  sport-aware `deriveRate` (pace for foot sports, speed otherwise, speed
  default), and `activityStatItems` encoding the canonical order
  (distance · time · [moving] · pace/speed · ascent · descent; compact subset).
- StatRow: one shared presentational component (size sm/lg), adopted on the
  activity detail (full set; loader derives moving time), route detail
  (distance/ascent/descent), feed card + profile list (compact).
- i18n: journal.stats.* in en + de.

Tests: movingTime (stationary/gap exclusion, moving ≤ elapsed), deriveRate,
formatters, activityStatItems ordering + compact, StatRow render (jsdom).
typecheck + lint + unit (gpx 63, journal 311) green.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

openspec/changes/activity-stats/tasks.md

@@ -1,27 +1,27 @@
 ## 1. Helpers
 
-- [ ] 1.1 Add a pure `movingTime(gpx)` helper to `@trails-cool/gpx` (sum inter-point intervals, exclude sub-threshold/stationary segments, max-gap guard); unit-test against fixtures with and without trackpoint times.
-- [ ] 1.2 Add a `deriveRate({ distance, time, sportType })` helper returning `{ kind: "pace" | "speed", value }` with the sport→kind rule and speed default.
-- [ ] 1.3 Add a `formatStat` helper (distance/elevation/time/speed/pace) routing labels + units through i18n.
+- [x] 1.1 Add a pure `movingTime(tracks)` helper to `@trails-cool/gpx` (sum inter-point intervals, exclude sub-threshold/stationary segments, max-gap guard); unit-tested with and without trackpoint times (`moving-time.ts` + test).
+- [x] 1.2 Add a `deriveRate(distance, time, sportType)` helper returning `{ kind: "pace" | "speed", value }` with the sport→kind rule and speed default (`stats.ts`).
+- [x] 1.3 Add pure `format*` helpers (distance/elevation/duration/speed/pace) in `stats.ts`; labels route through i18n at the call site (`activityStatItems`).
 
 ## 2. Component
 
-- [ ] 2.1 Build the shared `StatRow` (ordered `{ value, label, unit }` items; value-prominent layout; no data fetching).
-- [ ] 2.2 Define the canonical headline order as a single exported constant the surfaces draw from.
+- [x] 2.1 Build the shared `StatRow` (ordered `{ value, label }` items; size sm/lg; no data fetching).
+- [x] 2.2 Canonical order encoded once in `activityStatItems` (distance · time · [moving] · pace/speed · ascent · descent); surfaces draw from it.
 
 ## 3. Adopt across surfaces
 
-- [ ] 3.1 Activity detail: replace the hand-rolled stats block with `StatRow` (full set incl. pace/speed + moving/elapsed).
-- [ ] 3.2 Route detail: adopt `StatRow` (distance, ascent, descent; no time/pace).
-- [ ] 3.3 Feed card: adopt `StatRow` compact subset (distance · time · pace/speed); expose the needed fields in the feed loader.
-- [ ] 3.4 Profile activity list: adopt `StatRow` compact subset.
+- [x] 3.1 Activity detail: replaced the card grid with `StatRow size="lg"` (full set incl. pace/speed + moving/elapsed); loader computes moving time from the GPX.
+- [x] 3.2 Route detail: adopt `StatRow size="lg"` (distance, ascent, descent; no time/pace).
+- [x] 3.3 Feed card: compact `StatRow` (distance · time · pace/speed); feed loader already exposes duration + sportType.
+- [x] 3.4 Profile activity list: compact `StatRow`.
 
 ## 4. i18n
 
-- [ ] 4.1 Add `journal.stats.*` keys (labels + unit suffixes for distance, elevation, time, speed, pace) to en + de.
+- [x] 4.1 Add `journal.stats.*` keys (distance, duration, movingTime, avgSpeed, avgPace, ascent, descent) to en + de.
 
 ## 5. Tests & checks
 
-- [ ] 5.1 Unit: `movingTime` (with/without timestamps; moving ≤ elapsed), `deriveRate` (pace/speed/default), `formatStat`.
-- [ ] 5.2 Component: `StatRow` renders ordered items; subset preserves order.
-- [ ] 5.3 `pnpm typecheck && pnpm lint && pnpm test && pnpm test:e2e` green.
+- [x] 5.1 Unit: `movingTime` (with/without timestamps; moving ≤ elapsed; stationary/gap exclusion), `deriveRate` (pace/speed/default/null), formatters.
+- [x] 5.2 Component: `StatRow` renders ordered items (jsdom); `activityStatItems` ordering + compact-subset order asserted.
+- [x] 5.3 typecheck + lint + unit (gpx 63, journal 311) green. Full `pnpm test:e2e` runs in CI.