fix: postgres WAL corruption recovery + memory bump + researcher/executor

- Postgres memory: 256M→384M limits, 64M→96M reservations
- Added pg_resetwal -f pre-deploy step to recover from corrupt WAL
  ('PANIC: could not locate a valid checkpoint record' caused by
  force-killed postgres during --force-recreate)
- Added data-checksums initdb arg for future corruption detection
- api→postgres and web→api depends_on: service_healthy→service_started
- Deploy wait loop: fail fast on unhealthy, wait on starting (180s)
- Added researcher/executor to ValidAssignees and frontend dropdowns

frontend/src/views/TaskBoardView.vue

@@ -226,6 +226,8 @@ function expectedFromLabel(expected: string | null | undefined): string {
     'programmer': '🛠 Programmer',
     'reviewer': '🔎 Reviewer',
     'architekt': '🏛 Architekt',
+    'researcher': '🔬 Researcher',
+    'executor': '⚡ Executor',
   }
   return map[expected.toLowerCase()] ?? expected
 }
@@ -778,6 +780,8 @@ onUnmounted(() => {
                   <option value="programmer">🛠 Programmer</option>
                   <option value="reviewer">🔎 Reviewer</option>
                   <option value="architekt">🏛 Architekt</option>
+                  <option value="researcher">🔬 Researcher</option>
+                  <option value="executor">⚡ Executor</option>
                 </select>
               </div>
             </div>
@@ -896,6 +900,8 @@ onUnmounted(() => {
                     <option value="programmer">🛠 Programmer</option>
                     <option value="reviewer">🔎 Reviewer</option>
                     <option value="architekt">🏛 Architekt</option>
+                    <option value="researcher">🔬 Researcher</option>
+                    <option value="executor">⚡ Executor</option>
                   </select>
                 </label>
                 <label class="sidebar-field">