feat(dashboard): Recent activity events route to entity by kind

SP21 Task 2.5 — the Dashboard's 'Recent activity' card now routes clicks
to the matching entity drawer / page by event kind:

  - claim_*       → /claims?claim=<id>  (drawer in Phase 5)
  - provider_added → /providers?provider=<npi>  (ProviderDrawer)
  - remit_received → toast 'coming in a later phase' (RemitDrawer in Phase 4)
  - anything else  → toast (manual_match, unknown kinds)

Implementation:
  - New src/lib/event-routing.ts with the eventKindToUrl() helper,
    plus a unit test covering all 6 + default branches.
  - src/components/ActivityFeed.tsx gains an optional onItemClick
    prop; when set, each row gets role='button', tabIndex=0, the
    drillable hover affordance (chevron + tint), and an Enter/Space
    keybinding. e.stopPropagation() is called before the handler so a
    parent row click can't double-fire (same fix as Task 2.4).
  - src/pages/Dashboard.tsx wires the handler on the 'Recent activity'
    card via eventKindToUrl + sonner toast for unhandled kinds.
  - Backend: CycloneStore.recent_activity() now exposes claimId and
    remittanceId on each row (read from ActivityEvent.claim_id /
    remittance_id) so the routing helper has the entity ids it needs.
  - The frontend Activity interface gains optional claimId /
    remittanceId fields; the in-memory sample data and the
    addClaim store action populate them so the dashboard works in
    both API-configured and sample-data modes.

backend/src/cyclone/store.py

@@ -1668,7 +1668,16 @@ class CycloneStore:
             return list(by_npi.values())
 
     def recent_activity(self, *, limit: int = 200) -> list[dict]:
-        """Return recent activity events from the DB, newest first."""
+        """Return recent activity events from the DB, newest first.
+
+        SP21 Task 2.5: each row also carries ``claimId`` and
+        ``remittanceId`` (read from the ORM columns) so the Dashboard's
+        Recent-activity card can route clicks to the right entity
+        drawer via ``src/lib/event-routing.ts``. Both are nullable
+        strings; the wire shape uses camelCase keys to match the
+        existing ``npi`` / ``amount`` fields and the frontend
+        ``Activity`` interface.
+        """
         with db.SessionLocal()() as s:
             rows = (
                 s.query(ActivityEvent)
@@ -1684,6 +1693,8 @@ class CycloneStore:
                     "timestamp": r.ts.isoformat().replace("+00:00", "Z"),
                     "npi": (r.payload_json or {}).get("npi"),
                     "amount": (r.payload_json or {}).get("amount"),
+                    "claimId": r.claim_id,
+                    "remittanceId": r.remittance_id,
                 }
                 for r in rows
             ]