Point the USB flasher at web.esphome.io

Flip FLASHER_URL to the production web.esphome.io flasher and update the
release note: its postMessage receiver is esphome/dashboard#923, which
must be merged and deployed before a backend release bundles this.

Author: bdraco

src/common/docs.ts

@@ -5,16 +5,16 @@ export const ESPHOME_DOCS_BASE = "https://esphome.io";
  * Secure-context Web Serial flasher the dashboard hands firmware to over
  * postMessage (the HA add-on is plain http, so it can't run Web Serial itself).
  *
- * RELEASE GATE: this is the DEVELOPMENT target (GitHub Pages). It MUST be
- * flipped to web.esphome.io before any backend release bundles this frontend,
- * or HA add-on users would hand their factory image to a dev site. Tracked in
- * esphome/backlog#151; the companion web.esphome.io postMessage-ingest change
- * lands first. Until then PR #904 stays a draft (the actual merge gate).
+ * Production target: web.esphome.io. Its postMessage-ingest receiver is
+ * esphome/dashboard#923, which MUST be merged and deployed before a backend
+ * release bundles this frontend, or HA add-on users would hand their factory
+ * image to a web.esphome.io that doesn't yet accept it. Tracked in
+ * esphome/backlog#151.
  *
  * FLASHER_ORIGIN is the bare origin used for the postMessage targetOrigin and
  * for validating inbound frames.
  */
-export const FLASHER_URL = "https://esphome.github.io/device-builder/";
+export const FLASHER_URL = "https://web.esphome.io/";
 // Derived so the postMessage targetOrigin / inbound-frame check can't drift
 // from FLASHER_URL when the target moves to web.esphome.io.
 export const FLASHER_ORIGIN = new URL(FLASHER_URL).origin;