Reorganize Firefox configuration and repository documentation

- Configure Firefox with privacy settings and extensions (Bitwarden, Plasma Integration, MetaMask, Kagi Search, uBlock Origin)
- Set Kagi as default/only search engine
- Add MOZ_USE_XINPUT2=1 for smooth scrolling
- Create context/ directory for concise unit documentation
- Create tests/ directory for test scripts
- Move test-firefox-config.sh to tests/
- Update agents.md with documentation workflow guidelines
- Fix syntax errors in desktop.nix and dev.nix

context/firefox.md

@@ -0,0 +1,45 @@
+# Firefox Configuration
+
+**User:** jsutter  
+**Config:** `users/jsutter.nix` → `programs.firefox`
+
+## Extensions (Force Installed)
+- **uBlock Origin** - Ad blocker
+- **Bitwarden** - Password manager
+- **Plasma Integration** - KDE integration
+- **MetaMask** - Web3 wallet
+- **Kagi Search** - Default/only search engine
+
+## Key Settings
+- **Search:** Kagi only (all other engines removed)
+- **Homepage:** Blank page (`about:blank`)
+- **Privacy:** Strict content blocking, Do Not Track, fingerprinting resistance
+- **Telemetry:** Disabled
+- **Permissions:** Block location/notifications/autoplay/VR requests
+- **Tabs:** Ctrl+Tab cycles in recent order, hover previews disabled
+- **Performance:** Hardware acceleration enabled, smooth scrolling via `MOZ_USE_XINPUT2=1`
+
+## Build & Test
+```bash
+nixos-rebuild build --flake .#framework
+./tests/test-firefox-config.sh
+sudo nixos-rebuild switch --flake .
+```
+
+## Manual Setup Required
+- Sign in to Bitwarden
+- Sign in to MetaMask
+- Sign in to Kagi (for full features)
+- Set zoom per device in `about:config`:
+  - Framework: `layout.css.devPixelsPerPx = 1.1` (110%)
+  - Aurora: `layout.css.devPixelsPerPx = 1.2` (120%)
+
+## Verification
+- `about:policies` - Check policies are active
+- `about:preferences#privacy` - Verify privacy settings
+- Extensions auto-install on first Firefox launch
+
+## Notes
+- Extensions cannot be uninstalled (force installed via policy)
+- Settings are declarative and persist across updates
+- Title bar hiding requires manual UserChrome.css if desired