feat(factory): auto-sync latest bins after idf build

tools/esptool-factory/README.md

@@ -16,8 +16,14 @@ From project root:
 idf.py build
 ```
 
-The packaging script auto-syncs required plaintext build outputs from `build/flasher_args.json`
-into `tools/esptool-factory/bin/`, then encrypts them into `.bin.enc` for distribution.
+`idf.py build` now auto-overwrite-syncs required plaintext build outputs
+from `build/flasher_args.json` into `tools/esptool-factory/bin/`.
+
+If you already built firmware and only want to refresh bin files manually:
+
+```bash
+python3 tools/esptool-factory/sync_factory_bins.py
+```
 
 ### 2) Prepare private config
 
@@ -44,6 +50,14 @@ From project root:
 tools/esptool-factory/.venv/bin/python3 tools/esptool-factory/package_factory_tools.py
 ```
 
+By default, the packager now directly uses files in `tools/esptool-factory/bin/`.
+If you still want packager-side sync from `build/`, use:
+
+```bash
+tools/esptool-factory/.venv/bin/python3 tools/esptool-factory/package_factory_tools.py \
+  --sync-build-bins
+```
+
 The packager always uses:
 
 - `tools/esptool-factory/keys/firmware/fw_key.bin`