feat: remote browser login persistence + balance display + UI consistency

- Retain login state in remote browser profiles (don't delete on disconnect)
- Add GET /api/browser-sessions/{id}/clipboard for clipboard sync
- Add POST /api/browser-sessions/{id}/autofill-login for manual credential fill
- Add DELETE /api/browser-sessions/profiles/{custom_page_id} for login clear
- Add balance tracking with configurable divisor (balance_divisor)
- Health check on session reuse, idle TTL eviction, background cleanup
- Add first-frame watchdog (10s timeout) to prevent infinite loading
- Reconnect browser on active=true when session was closed
- UI: uniform text-only inline buttons (websites + upstreams pages)
- Fix page switch race with closingRemoteSessionPromise

backend/app/database.py

@@ -29,6 +29,7 @@ def init_db():
     from app.models import admin_user, upstream, snapshot, webhook_config, notification_log, custom_page, website, revoked_token  # noqa: F401
     Base.metadata.create_all(bind=engine)
     _migrate_custom_pages()
+    _migrate_upstreams()
 
 
 def _migrate_custom_pages():
@@ -67,3 +68,22 @@ def _migrate_custom_pages():
         if "linked_upstream_id" not in columns:
             conn.execute(text("ALTER TABLE custom_pages ADD COLUMN linked_upstream_id INTEGER"))
 
+
+def _migrate_upstreams():
+    """Apply SQLite-safe migrations to the upstreams table."""
+    inspector = inspect(engine)
+    if "upstreams" not in inspector.get_table_names():
+        return
+    columns = {col["name"] for col in inspector.get_columns("upstreams")}
+    with engine.begin() as conn:
+        if "balance" not in columns:
+            conn.execute(text("ALTER TABLE upstreams ADD COLUMN balance FLOAT"))
+        if "balance_updated_at" not in columns:
+            conn.execute(text("ALTER TABLE upstreams ADD COLUMN balance_updated_at DATETIME"))
+        if "balance_endpoint" not in columns:
+            conn.execute(text("ALTER TABLE upstreams ADD COLUMN balance_endpoint VARCHAR(256) NOT NULL DEFAULT ''"))
+        if "balance_response_path" not in columns:
+            conn.execute(text("ALTER TABLE upstreams ADD COLUMN balance_response_path VARCHAR(256) NOT NULL DEFAULT ''"))
+        if "balance_divisor" not in columns:
+            conn.execute(text("ALTER TABLE upstreams ADD COLUMN balance_divisor FLOAT NOT NULL DEFAULT 1.0"))
+