Enhance build system and logging configuration

- Add scripts/build.sh to compile binaries into bin/ directory

- Move all zerolog setup logic from cmd/server/main.go to pkg/config

- Add log level configuration support (trace, debug, info, warn, error, fatal, panic)

- Simplify cmd/server/main.go from 57 to 27 lines (53% reduction)

- Update .gitignore to use bin/ directory instead of individual files

- Document build process and bin directory in AGENTS.md

- Maintain backward compatibility with all existing functionality

AGENTS.md

@@ -355,12 +355,37 @@ go test ./...
 go test ./pkg/greet/
 ```
 
-### 5. Make Changes
+### 5. Build Binaries
+
+The project uses a build script to compile binaries into the `bin/` directory:
+
+```bash
+# Build both server and greet binaries
+./scripts/build.sh
+
+# This creates:
+# - ./bin/server - The web server binary
+# - ./bin/greet  - The CLI greeting tool
+```
+
+**Binary Usage:**
+```bash
+# Run the server
+./bin/server
+
+# Use the greet CLI
+./bin/greet          # Output: Hello world!
+./bin/greet John     # Output: Hello John!
+```
+
+**The `bin/` directory is gitignored** to prevent binary files from being committed to the repository.
+
+### 6. Make Changes
 - Edit source files in `pkg/` or `cmd/`
 - Follow existing patterns and interfaces
 - Add tests for new functionality
 
-### 6. Stop and Restart
+### 7. Stop and Restart
 ```bash
 ./scripts/start-server.sh restart
 ```