feat: portal cross-event my-shifts endpoint and dashboard page

GET /portal/my-shifts aggregates shift assignments across all events
the logged-in user is linked to via Person records. Groups by event
then date, showing only active assignments (approved/pending_approval)
for approved/pending persons.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

dev-docs/API.md

@@ -538,6 +538,47 @@ Response: `{ "confirmed": 2, "errors": [{ "match_id": "ulid3", "error": "User al
 
 - `POST /portal/token-auth` — public. Validates a portal token against artists/production_requests tables. Returns `{ context, data, event }` on success. Returns 501 if token tables don't exist yet, 401 if token is invalid.
 - `GET /portal/me` — auth:sanctum. Returns the authenticated user's person record for a given event. Query param: `event_id` (required, ULID). Resolves sub-events to parent festival. Returns `PersonResource` with crowdType, shiftAssignments, and volunteerAvailabilities eager-loaded. Returns 404 if no registration found.
+- `GET /portal/my-shifts` — auth:sanctum. Returns all active shift assignments across all events for the authenticated user. Finds all Person records linked via `user_id` (approved/pending status), then returns their active assignments (approved/pending_approval). Response grouped by event → date.
+- `GET /portal/events/{event}/available-shifts` — auth:sanctum. Returns shifts available to claim, grouped by date → time slot. Requires approved person status.
+- `GET /portal/events/{event}/my-shifts` — auth:sanctum. Returns the user's shift assignments for a specific event, categorized as upcoming/past/cancelled.
+- `POST /portal/events/{event}/shifts/{shift}/claim` — auth:sanctum. Claim a shift. Returns assignment with status (pending_approval or approved based on section auto-accept).
+- `POST /portal/events/{event}/assignments/{shiftAssignment}/cancel` — auth:sanctum. Cancel own assignment. Must be future and cancellable status.
+
+### Portal My-Shifts Response
+
+```json
+{
+  "data": [
+    {
+      "event": { "id": "ulid", "name": "Festival X", "start_date": "2026-07-01", "end_date": "2026-07-03" },
+      "assignments": [
+        {
+          "date": "2026-07-01",
+          "date_label": "Woensdag 1 juli",
+          "shifts": [
+            {
+              "id": "ulid",
+              "status": "approved",
+              "shift": {
+                "id": "ulid",
+                "title": "Tapper",
+                "section_name": "Bar",
+                "section_icon": "tabler-beer",
+                "time_slot_name": "Avond",
+                "date": "2026-07-01",
+                "start_time": "18:00",
+                "end_time": "23:00",
+                "report_time": "17:30",
+                "location": { "name": "Hoofdpodium", "address": "Festivalplein 1" }
+              }
+            }
+          ]
+        }
+      ]
+    }
+  ]
+}
+```
 
 ## Registration Field Templates (Organisation Settings)