feat: add Firefox extension support

- Add Firefox as an install target with native messaging manifest support.
- Generate Firefox-specific extension packages with Gecko metadata and AMO-compatible manifest transforms.
- Keep tab group commands available in Firefox through dynamic tab group API helpers.
- Avoid Firefox linter warnings for static tab group API references and direct eval tokens.
- Add Firefox packaging and installer regression coverage.
- Bump the package and extension version to 0.15.1.

README.md

@@ -50,7 +50,7 @@ Every response:
 
 ## Installation
 
-**Requirements:** Python 3.10+, [uv](https://github.com/astral-sh/uv), Chrome, Chromium, Brave, Edge, Vivaldi
+**Requirements:** Python 3.10+, [uv](https://github.com/astral-sh/uv), Chrome, Chromium, Brave, Edge, Vivaldi, or Firefox
 
 ### Install with uv
 Once published on PyPI, install the CLI as a uv tool:
@@ -58,7 +58,7 @@ Once published on PyPI, install the CLI as a uv tool:
 ```sh
 uv tool install real-browser-cli
 browser-cli --version
-browser-cli install brave   # or: chrome, chromium, edge, vivaldi
+browser-cli install brave   # or: chrome, chromium, edge, vivaldi, firefox
 ```
 
 The PyPI package is named `real-browser-cli`; the installed command is still `browser-cli`.
@@ -80,12 +80,12 @@ uv tool upgrade real-browser-cli
 git clone <repo>
 cd browser-cli
 uv sync
-uv run browser-cli install brave   # or: chrome, chromium, edge, vivaldi
+uv run browser-cli install brave   # or: chrome, chromium, edge, vivaldi, firefox
 ```
 
 The `install` command will:
 1. Ask you to load the browser-specific extension package
-2. For Chromium-family browsers, ask you to paste the extension ID shown on the extension card
+2. Show the stable extension ID used by that browser family
 3. Write the native messaging manifest to your OS so the browser can find the host
 4. Copy the native host into an internal `libexec` directory and create a small wrapper outside your `PATH`
 
@@ -515,11 +515,12 @@ The extension source lives in `extension/src/`. `extension/background.js` and `e
 Packaging:
 
 ```bash
-npm run package:extension           # testing/unpacked zip, keeps manifest.key for stable native-messaging ID
+npm run package:extension           # testing/unpacked zip, keeps manifest.key for stable Chromium native-messaging ID
 npm run package:extension:webstore  # Chrome Web Store zip, strips manifest.key
+npm run package:extension:firefox   # Firefox zip, strips manifest.key and Firefox-incompatible permissions
 ```
 
-Chrome Web Store rejects `manifest.key`, so upload the `*-webstore-*` zip from `dist/`.
+Chrome Web Store rejects `manifest.key`, so upload the `*-webstore-*` zip from `dist/`. For Firefox, use the `*-firefox-*` zip.
 
 ---
 
@@ -527,8 +528,8 @@ Chrome Web Store rejects `manifest.key`, so upload the `*-webstore-*` zip from `
 
 - **Browser internal pages** (`chrome://`, `brave://`, `edge://`, `about:`) cannot be scripted. DOM and extract commands only work on regular `http://` and `https://` pages.
 - **Multiple browser instances can be auto-distinguished, but generated aliases are temporary**. Unaliased browsers get UUID aliases from the native host, which avoids collisions but is less ergonomic than setting a stable alias with `browser-cli clients rename --browser <current-alias> <new-alias>`.
-- **Supported install targets are explicit, not “all Chromium browsers”**. The installer currently supports Chrome, Chromium, Brave, Edge, and Vivaldi. Other Chromium-based browsers may use different or shared native messaging manifest locations, so they need browser-specific verification before being added safely.
-- **Linux and macOS only** — Windows native messaging paths are not yet handled.
+- **Supported install targets are explicit, not “all Chromium browsers”**. The installer currently supports Chrome, Chromium, Brave, Edge, Vivaldi, and Firefox. Other Chromium-based browsers may use different or shared native messaging manifest locations, so they need browser-specific verification before being added safely.
+- **Firefox support is experimental**. Basic tab/window/navigation/native-messaging support is wired, including tab-group APIs on supported Firefox versions.
 
 ---