🤖 Update docs: macOS DMGs are now signed and notarized (#98)

Simplified installation instructions now that proper code signing and
notarization are in place (from #90).

## Changes

- **docs/install.md**: Removed all Gatekeeper bypass instructions
(right-click → Open, terminal workarounds)
- **docs/install.md**: Clarified separate x64 and arm64 artifact names
- **README.md**: Updated to note signed/notarized status

## User Impact

Users can now install cmux on macOS without any security warnings or
workarounds. The app opens normally like any other Mac application.

_Generated with `cmux`_

Author: ammario

README.md

@@ -19,7 +19,7 @@ A cross-platform desktop application for embarassingly parallel development.
 
 Download pre-built binaries from [GitHub Actions artifacts](https://github.com/coder/cmux/actions/workflows/build.yml):
 
-- **macOS**: Universal binary DMG (Intel + Apple Silicon)
+- **macOS**: Signed and notarized DMG (separate builds for Intel/Apple Silicon)
 - **Linux**: AppImage
 
 ## Development

docs/install.md

@@ -6,42 +6,42 @@
 
 Pre-built binaries are available from [GitHub Actions](https://github.com/coder/cmux/actions/workflows/build.yml):
 
-- **macOS**: Universal binary DMG (Intel + Apple Silicon)
+- **macOS**: Signed and notarized DMG
+  - `macos-dmg-x64` (Intel Macs)
+  - `macos-dmg-arm64` (Apple Silicon)
 - **Linux**: AppImage (portable, works on most distros)
 
 To download:
 
 1. Go to the [Build workflow](https://github.com/coder/cmux/actions/workflows/build.yml)
 2. Click on the latest successful run
 3. Scroll down to "Artifacts" section
-4. Download `macos-dmg` or `linux-appimage`
+4. Download the appropriate artifact for your platform
 
 ### Installation
 
 **macOS:**
 
-⚠️ **Note**: The app is unsigned, so you'll need to bypass Gatekeeper security.
+1. Download the DMG file for your Mac:
+   - Intel Mac: `macos-dmg-x64`
+   - Apple Silicon: `macos-dmg-arm64`
+2. Open the DMG file
+3. Drag Cmux to Applications folder
+4. Open the app normally
 
-1. Download and open the DMG file
-2. Drag Cmux to Applications folder
-3. **First time opening**:
-   - Don't double-click the app (macOS will block it)
-   - Right-click (or Control+click) on Cmux.app
-   - Select "Open" from the menu
-   - Click "Open" in the security dialog
-   - The app will now be allowed to run
-
-**Alternative method if the above doesn't work:**
-
-1. After step 2, open Terminal
-2. Run: `xattr -cr /Applications/Cmux.app`
-3. Run: `codesign --force --deep --sign - /Applications/Cmux.app`
-4. Now you can open the app normally
-
-These steps are only needed once. After that, you can open the app normally.
+The app is code-signed and notarized by Apple, so it will open without security warnings.
 
 **Linux:**
 
 1. Download the AppImage file
 2. Make it executable: `chmod +x Cmux-*.AppImage`
 3. Run it: `./Cmux-*.AppImage`
+
+### Testing Pre-Release Builds
+
+⚠️ **Note**: Only builds from the `main` branch are signed and notarized. If you're testing a build from a pull request or other branch, you'll need to bypass macOS Gatekeeper:
+
+1. After installing, open Terminal
+2. Run: `xattr -cr /Applications/Cmux.app`
+3. Run: `codesign --force --deep --sign - /Applications/Cmux.app`
+4. Now you can open the app normally