feat: registration section preferences with show_in_registration filtering and deduplication

Add show_in_registration and registration_description columns to festival_sections.
Registration form now shows deduplicated sections by name (across sub-events),
filtered by show_in_registration=true, grouped by category with card-based UI.
Section preferences use section_name instead of section_id.
Add GET/PUT registration-settings endpoints for festival-level bulk management.

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

dev-docs/API.md

@@ -102,6 +102,43 @@ Returns 422 with `errors`, `current_status`, `requested_status`, and `allowed_tr
 > Shifts on cross_event sections must use the **parent festival's event_id** in API calls,
 > since the section's `event_id` points to the parent.
 
+### Registration Settings (Festival-level bulk management)
+
+- `GET /events/{event}/sections/registration-settings` — returns unique section names across the festival with registration visibility, description, and counts
+- `PUT /events/{event}/sections/registration-settings` — bulk update registration visibility for a section name across all instances in the festival
+
+#### GET Response
+
+```json
+{
+  "data": [
+    {
+      "name": "Hoofdpodium Bar",
+      "category": "Bar",
+      "icon": "tabler-beer",
+      "show_in_registration": true,
+      "registration_description": "Tap bier en drankjes voor festivalgangers",
+      "section_count": 3,
+      "section_ids": ["ulid1", "ulid2", "ulid3"]
+    }
+  ]
+}
+```
+
+#### PUT Body
+
+```json
+{
+  "name": "Hoofdpodium Bar",
+  "show_in_registration": true,
+  "registration_description": "Tap bier en drankjes voor festivalgangers"
+}
+```
+
+Returns the full updated registration-settings response. Creates activity log `section.registration_settings_updated`.
+
+Auth: org_admin or event_manager on the event's organisation.
+
 ## Time Slots
 
 - `GET /events/{event}/time-slots`
@@ -391,7 +428,7 @@ Response: `{ "confirmed": 2, "errors": [{ "match_id": "ulid3", "error": "User al
 
 ## Public Registration Data
 
-- `GET /public/events/{slug}/registration-data` — public, no auth. Returns event info, available sections, and volunteer time slots for the registration form. Only returns events with status `registration_open`. Excludes `cross_event` sections. Only includes time slots with `person_type = VOLUNTEER`. Resolves sub-events to parent festival.
+- `GET /public/events/{slug}/registration-data` — public, no auth. Returns event info, available sections, and volunteer time slots for the registration form. Only returns events with status `registration_open`. Only includes sections with `show_in_registration = true` and `type = standard`. For festivals: returns child event sections only (deduplicated by name), excluding parent operational sections. Only includes time slots with `person_type = VOLUNTEER`. Resolves sub-events to parent festival.
 
 ### Response
 
@@ -399,7 +436,7 @@ Response: `{ "confirmed": 2, "errors": [{ "match_id": "ulid3", "error": "User al
 {
   "data": {
     "event": { "id": "01JXYZ...", "name": "Echt Feesten 2026", "start_date": "2026-07-10", "end_date": "2026-07-12", "organisation_id": "01JXYZ..." },
-    "sections": [{ "id": "01JXYZ...", "name": "Hoofdpodium Bar", "category": "Bar", "icon": "tabler-glass" }],
+    "sections": [{ "id": "01JXYZ...", "name": "Hoofdpodium Bar", "category": "Bar", "icon": "tabler-glass", "registration_description": "Tap bier en drankjes voor festivalgangers" }],
     "time_slots": [{ "id": "01JXYZ...", "name": "Vrijdag Avond", "date": "2026-07-10", "start_time": "18:00:00", "end_time": "02:00:00", "duration_hours": 8 }]
   }
 }

dev-docs/SCHEMA.md

@@ -295,6 +295,8 @@ scopeFestivals()    // WHERE event_type IN ('festival', 'series')
 | `crew_accreditation_level`        | string nullable    | **v1.5** Default accreditation level for crew (e.g. AAA, AA, A)   |
 | `public_form_accreditation_level` | string nullable    | **v1.5** Accreditation level for public form registrants          |
 | `timed_accreditations`            | bool               | **v1.5** Accreditations are time-limited for this section         |
+| `show_in_registration`            | bool               | **v1.8** Show this section in the volunteer registration form     |
+| `registration_description`        | text nullable      | **v1.8** Description shown to volunteers in the registration form |
 | `deleted_at`                      | timestamp nullable | Soft delete                                                       |
 
 **Relations:** `hasMany` shifts  
@@ -309,6 +311,7 @@ scopeFestivals()    // WHERE event_type IN ('festival', 'series')
 - `added_to_timeline`: false
 - `responder_self_checkin`: true
 - `timed_accreditations`: false
+- `show_in_registration`: false
 
 > **Note:** "Overkoepelende" sections (shared across all sub-events of a festival)
 > are identified by `type = 'cross_event'`. There is no separate `is_shared` boolean