Implement Backend API, MCP Server, and Gitea integration

- Add REST API routes for projects, tasks, and agents (CRUD operations)
- Implement MCP Server with 4 core tools:
  - get_next_task: Assign tasks to agents
  - update_task_status: Update task states
  - create_branch: Create Git branches via Gitea API
  - create_pull_request: Create PRs via Gitea API
- Add Gitea API client for repository operations
- Fix database migration error handling for existing tables
- Connect all routes to Bun.serve() main server

Co-Authored-By: Claude Sonnet 4.5 (1M context) <noreply@anthropic.com>

src/db/migrate.ts

@@ -25,7 +25,22 @@ export async function runMigrations() {
     console.log('✅ Migrations completed successfully')
     await connection.end()
     return true
-  } catch (error) {
+  } catch (error: any) {
+    // If table already exists, it's not a fatal error
+    const errorMessage = error?.message || String(error)
+    const errorCode = error?.code || error?.cause?.code
+    const errorErrno = error?.errno || error?.cause?.errno
+
+    if (
+      errorCode === 'ER_TABLE_EXISTS_ERROR' ||
+      errorErrno === 1050 ||
+      errorMessage.includes('already exists')
+    ) {
+      console.log('⚠️  Tables already exist, skipping migrations')
+      await connection.end()
+      return true
+    }
+
     console.error('❌ Migration failed:', error)
     await connection.end()
     throw error