feat(api): mobile API Milestone 4 — full PUSH (inspections/issues/features + conflicts)

SyncController now handles the full mutation vocabulary:
- inspection.create (idempotent by uuid; project/layer derived from feature;
  authz member + 'create inspections'; status defaults to completed).
- issue.create (idempotent; authz member + 'create issues').
- issue.update (by server id; authz member + 'edit issues'; sets resolved_at
  when resolved/closed; last-write-wins conflict).
- feature.update (by server id; authz member + 'update progress'; recomputes
  phase progress; last-write-wins conflict).
- Conflict detection: client_updated_at vs server updated_at → returns
  'conflict' with the current server value.
Added uuid + client_updated_at to features/inspections/issues (guarded migration)
and their fillables. Tests: 16 passing (added inspection/issue/feature + conflict).

Note: 2 PRE-EXISTING test failures remain (not from this work, sqlite-only):
ExampleTest expects '/'=200 (app redirects), and the dashboard route uses MySQL
FIELD() which sqlite lacks.

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

app/Models/Inspection.php

@@ -16,6 +16,7 @@ class Inspection extends Model
     protected $fillable = [
         'project_id', 'layer_id', 'feature_id', 'template_id', 'user_id',
         'data', 'status', 'inspector_user_id', 'completed_at', 'result', 'notes',
+        'uuid', 'client_updated_at',
     ];
 
     protected $casts = [