Format and lint codebase for consistency and quality

- Run go fmt on all Go code (server.go formatting cleanup)
- Fix shellcheck issues in build-deb.sh script:
  - Replace indirect exit code checks ($?) with direct command checks
  - Use 'if ! command' instead of 'if [ $? -ne 0 ]'
  - Use 'if command' instead of 'if [ $? -eq 0 ]'
- All quality checks now pass:
  - go fmt: ✅ Code properly formatted
  - go vet: ✅ No issues found
  - shellcheck: ✅ All shell scripts validated
  - go test: ✅ No test failures (no tests yet)

Follows project guidelines for shell script validation and code quality.

🤖 Generated with [Claude Code](https://claude.ai/code)

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

internal/server/server.go

@@ -149,7 +149,7 @@ func (s *Server) Start() error {
 		// IPv6 address needs brackets
 		addr = fmt.Sprintf("[%s]:%d", s.host, s.port)
 	}
-	
+
 	s.server = &http.Server{
 		Addr:    addr,
 		Handler: router,