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>

database/migrations/2026_06_18_073000_add_sync_fields_to_syncable_tables.php

@@ -0,0 +1,37 @@
+<?php
+
+use Illuminate\Database\Migrations\Migration;
+use Illuminate\Database\Schema\Blueprint;
+use Illuminate\Support\Facades\Schema;
+
+return new class extends Migration
+{
+    private array $tables = ['features', 'inspections', 'issues'];
+
+    public function up(): void
+    {
+        foreach ($this->tables as $name) {
+            Schema::table($name, function (Blueprint $table) use ($name) {
+                if (! Schema::hasColumn($name, 'uuid')) {
+                    $table->uuid('uuid')->nullable()->unique()->after('id');
+                }
+                if (! Schema::hasColumn($name, 'client_updated_at')) {
+                    $table->timestamp('client_updated_at')->nullable();
+                }
+            });
+        }
+    }
+
+    public function down(): void
+    {
+        foreach ($this->tables as $name) {
+            Schema::table($name, function (Blueprint $table) use ($name) {
+                foreach (['uuid', 'client_updated_at'] as $col) {
+                    if (Schema::hasColumn($name, $col)) {
+                        $table->dropColumn($col);
+                    }
+                }
+            });
+        }
+    }
+};