feat: Update documentation for version 0.9.1, including changelog, configuration, and package manager support

CONFIG_README.md

@@ -36,7 +36,10 @@ Create a `config.json` file with the following structure:
   "log_file": "logs/webdrop_bridge.log",
   "window_width": 1024,
   "window_height": 768,
-  "enable_logging": true
+  "enable_logging": true,
+  "language": "auto",
+  "active_branding_id": "default",
+  "brand_id": "agravity"
 }
 ```
 
@@ -99,6 +102,19 @@ Z:\aN5PysnXIuRECzcRbvHkjL7g0\Hintergrund_Agravity.png
 - **`window_width`**, **`window_height`** (number): Initial window size in pixels
   - Default: `1024` x `768`
 
+### Language and Branding Settings
+
+- **`language`** (string): UI language code
+  - Use `"auto"` to follow the system locale automatically
+  - Bundled translations currently include `en`, `de`, `fr`, `it`, `ru`, and `zh`
+
+- **`active_branding_id`** (string): Runtime branding template selected in the Settings dialog
+  - Default: `"default"`
+  - Useful when switching between saved branding templates without rebuilding the app
+
+- **`brand_id`** (string): Stable packaging/update identifier for branded variants
+  - Usually injected during packaging and normally left unchanged by end users
+
 - **`log_level`** (string): Logging verbosity
   - Options: `"DEBUG"`, `"INFO"`, `"WARNING"`, `"ERROR"`, `"CRITICAL"`
   - Default: `"INFO"`
@@ -149,6 +165,14 @@ You can configure multiple Azure storage accounts:
 }
 ```
 
+## Configuration Priority
+
+At startup, WebDrop Bridge first loads any bootstrap `.env` defaults and then prefers the persisted JSON config if it exists. This means:
+
+1. packaged or development defaults can still come from `.env`,
+2. the Settings dialog saves the active runtime configuration to JSON, and
+3. the JSON file becomes the main configuration source after first save.
+
 ## Environment Variable Fallback
 
 If no JSON config exists, WebDrop Bridge will load from `.env`: