feat(journal): Garmin activity import — provider, webhook pipeline, backfill (§1–5)

Garmin Connect as the third connected-services provider (spec:
garmin-import). The interesting parts:

- Push-first ingestion: Garmin has no list endpoint. The webhook
  normalizes ping (callbackURL) and push (inline) notification batches
  into events; the slow work (authorized FIT download, FIT→GPX via the
  shared converter, activity creation) runs in a garmin-import-activity
  pg-boss job so the webhook answers fast. Callback URLs are validated
  against Garmin's API host before any fetch (SSRF guard).
- History via backfill requests: /sync/import/garmin is a date-range
  requester with honest async progress (no pick list — the concept
  doesn't exist in a push model). Ranges chunk to Garmin's 90-day cap;
  overlaps are free via sync_imports dedupe. Requests persist in
  import_batches via two new nullable columns (range_start/range_end).
- OAuth2 + PKCE on the existing oauth credential kind. Design
  correction from apply: the verifier rides a short-lived httpOnly
  cookie scoped to the callback path — the state param is visible in
  redirect URLs and must never carry it. Manifests opt in via pkce:true.
- Deregistration notifications flip the connection to 'revoked'
  (row kept for audit, imports retained, re-connect prompt shown).
- Framework evolutions, all additive: parseWebhook returns
  WebhookEvent[] (Garmin batches; Wahoo adapted), manifest gains
  configured()/importUrl/pkce, importActivity accepts summary stats
  for FIT-less imports, manager gains markRevoked.
- Env-gated: no GARMIN_CLIENT_ID → provider hidden on
  /settings/connections. Privacy manifest entry (DE+EN). i18n en+de.

Rollout (§6) stays gated on the Garmin Developer Program application
(submitted 2026-06-07). Fixtures are doc-shaped; the staging soak
swaps in recorded payloads if shapes differ.

Gate: typecheck ✓ lint ✓ unit+integration ✓ e2e 70/72 + both known
flakes green isolated ✓ openspec validate ✓

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

apps/journal/.env.example

@@ -49,6 +49,14 @@
 # WAHOO_CLIENT_SECRET=
 # WAHOO_WEBHOOK_TOKEN=
 
+# Garmin Connect Developer Program credentials (spec: garmin-import).
+# Requires an approved program application; without these the Garmin
+# provider is hidden on /settings/connections. The OAuth callback to
+# register with Garmin is `<origin>/api/sync/callback/garmin`, the
+# notification endpoint `<origin>/api/sync/webhook/garmin`.
+# GARMIN_CLIENT_ID=
+# GARMIN_CLIENT_SECRET=
+
 # Integration test secret (only needed if running the integration
 # test suite that drives the API directly). Generate with
 # `openssl rand -hex 32`.