feat: API key management improvements

- Rename routes: /dashboard/tokens → /dashboard/apikeys, /dashboard/manager/keys → /dashboard/manager/channels
- Add KeyPlain field to store plaintext API keys for re-viewing
- API key list shows masked key (sk-ot-123456****abcd) with eye toggle to reveal
- Copy button with 2s feedback on key list
- TokenNew shows full key + copy after creation
- Increase key prefix display to 12 characters
- Fix SQLite driver: replace gorm.io/driver/sqlite with ncruces/go-sqlite3/gormlite
- Fix user.status === 'active' checks across frontend views
- Add channel store for new channels API
- Update Makefile frontend build to work reliably

BREAKING CHANGE: Existing API keys created before this change will not show their plaintext value (only prefix visible).

Makefile

@@ -1,12 +1,18 @@
-.PHONY: build run test clean fmt lint
+.PHONY: build run test clean fmt lint frontend
 
 BINARY_NAME=openteam
 BUILD_DIR=bin
 BACKEND_DIR=backend
 
 # Build
-build:
-	cd $(BACKEND_DIR) && CGO_ENABLED=1 go build -o ../$(BUILD_DIR)/$(BINARY_NAME) ./cmd/openteam
+build: frontend
+	cd $(BACKEND_DIR) && CGO_ENABLED=0 go build -o ../$(BUILD_DIR)/$(BINARY_NAME) ./cmd/openteam
+
+# Build frontend and copy dist
+frontend:
+	cd frontend && pnpm install && pnpm build
+	rm -rf $(BACKEND_DIR)/cmd/openteam/dist
+	cp -r frontend/dist $(BACKEND_DIR)/cmd/openteam/dist
 
 # Run
 run: build