refactor: Externalize web UI to index.html

Refactors the embedded web UI in the API server to be loaded from a
separate index.html file instead of a large inline string.

This improves maintainability by separating the presentation layer
(HTML/CSS/JS) from the backend Python logic.

fichero_printer/CHANGELOG.md

@@ -1,5 +1,21 @@
 # Changelog
 
+## 0.1.20
+
+- Refactored the embedded web UI to be loaded from an external `index.html` file.
+
+## 0.1.19
+
+- Added "Unpair Device" button to the web UI.
+
+## 0.1.18
+
+- Added "Pair Device" button to the web UI.
+
+## 0.1.16
+
+- Added automatic fallback to BLE if Classic Bluetooth fails with `[Errno 12] Out of memory`.
+
 ## 0.1.15
 
 - Added a BLE recovery retry for `br-connection-not-supported` that forces fresh LE target resolution from scan results before failing.