Prepare cladm for npm publishing

Add files field, author, repository, and engines to package.json. Add
.npmignore, MIT LICENSE file, GitHub Actions publish workflow on v* tags,
and update README install section with bun install -g / bunx instructions.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

README.md

@@ -19,17 +19,22 @@
 Requires [Bun](https://bun.sh) >= 1.3.0 and macOS (uses Terminal.app for launching).
 
 ```bash
-# Clone and install
+# Install globally
+bun install -g cladm
+
+# Or run directly
+bunx cladm
+```
+
+### From source (for development)
+
+```bash
 git clone https://github.com/alezmad/cladm.git
 cd cladm
 bun install
-
-# Register the `cladm` command globally
 bun link
 ```
 
-Now you can run `cladm` from anywhere.
-
 ## Usage
 
 ```bash