Add quiet input to suppress info-level log output

When quiet: true, only warnings and errors are logged.
All info calls are routed through a new logging module that
reads the quiet input via core.getInput on first use.

- Add src/utils/logging.ts with lazy-initialized quiet flag
- Add quiet boolean input to action.yml and action-types.yml
- Add quiet to SetupInputs interface and loadInputs()
- Replace core.info/core.warning with log.info/log.warning
  across all source files
- Keep ##[add-matcher] workflow command on core.info directly
  to avoid suppressing it in quiet mode
- Update README with new input

src/utils/logging.ts

@@ -0,0 +1,21 @@
+import * as core from "@actions/core";
+
+let quiet: boolean | undefined;
+
+function isQuiet(): boolean {
+  if (quiet === undefined) {
+    quiet =
+      typeof core.getInput === "function" && core.getInput("quiet") === "true";
+  }
+  return quiet;
+}
+
+export function info(msg: string): void {
+  if (!isQuiet()) {
+    core.info(msg);
+  }
+}
+
+export const warning = core.warning;
+export const error = core.error;
+export const debug = core.debug;