GRM-13: feat: replace print() with stdlib logging module

- Create logging_config.py with get_logger() providing dual handlers:
  - Console handler (stderr) controlled by GRM_LOG_LEVEL env var (default INFO)
  - File handler (~/.local/state/grm/logs/grm.log) capturing everything at DEBUG
- Replace all print() calls in executor.py and report.py with logger.info()/error()
- Add error logging before raising AnsibleError in executor.run()
- Add GRM_LOG_LEVEL to README configuration table and logging documentation
- Update all unit tests to mock logger instead of using capsys
- 114 tests, 100% coverage, pyright clean, ruff clean

src/gitea_runner_manager/executor.py

@@ -10,6 +10,7 @@ from pathlib import Path
 
 from .exceptions import AnsibleError
 from .i18n import _
+from .logging_config import get_logger
 
 
 class AnsibleExecutor:
@@ -17,31 +18,32 @@ class AnsibleExecutor:
 
     def __init__(self, log_dir: Path | None = None) -> None:
         self._log_dir = log_dir or Path.home() / ".local" / "state" / "grm" / "logs"
+        self._logger = get_logger()
 
     def run(self, cmd: list[str], description: str = "") -> None:
         """Run an Ansible command, redirecting output to a log file."""
         log_file = self._prepare_log(cmd)
         desc = description or _("Running Ansible playbook")
 
-        print(f"[GRM] {desc}")
-        print(f"[GRM] {_('Full log: {log_file}', log_file=log_file)}")
+        self._logger.info(desc)
+        self._logger.info(_("Full log: {log_file}", log_file=log_file))
 
         returncode = self._stream(cmd, log_file)
 
         if returncode != 0:
-            raise AnsibleError(
-                _(
-                    "Ansible failed with exit code {code}. See full log: {log_file}",
-                    code=returncode,
-                    log_file=log_file,
-                )
+            msg = _(
+                "Ansible failed with exit code {code}. See full log: {log_file}",
+                code=returncode,
+                log_file=log_file,
             )
+            self._logger.error(msg)
+            raise AnsibleError(msg)
 
         status = self._extract_status(log_file)
         if status:
-            print(f"[GRM] {status}")
+            self._logger.info(status)
 
-        print(f"[GRM] {_('Done. See full log: {log_file}', log_file=log_file)}")
+        self._logger.info(_("Done. See full log: {log_file}", log_file=log_file))
 
     def _prepare_log(self, cmd: list[str]) -> Path:
         """Create a log file with header."""

src/gitea_runner_manager/logging_config.py

@@ -0,0 +1,46 @@
+"""GRM logging configuration using the standard library."""
+
+from __future__ import annotations
+
+import logging
+import os
+from pathlib import Path
+
+
+def get_logger(name: str = "grm") -> logging.Logger:
+    """Return a configured logger for GRM.
+
+    Console output respects ``GRM_LOG_LEVEL`` (default: INFO).
+    All messages are also written to ``~/.local/state/grm/logs/grm.log``.
+    """
+    logger = logging.getLogger(name)
+    if logger.handlers:
+        return logger
+
+    logger.setLevel(logging.DEBUG)
+
+    # Console handler — user-controlled level
+    console = logging.StreamHandler()
+    console.setLevel(_level_from_env(os.getenv("GRM_LOG_LEVEL", "INFO")))
+    console.setFormatter(logging.Formatter("[GRM] %(message)s"))
+    logger.addHandler(console)
+
+    # File handler — captures everything including DEBUG
+    log_dir = Path.home() / ".local" / "state" / "grm" / "logs"
+    log_dir.mkdir(parents=True, exist_ok=True)
+    file_handler = logging.FileHandler(log_dir / "grm.log")
+    file_handler.setLevel(logging.DEBUG)
+    file_handler.setFormatter(logging.Formatter("%(asctime)s %(levelname)s %(name)s: %(message)s"))
+    logger.addHandler(file_handler)
+
+    return logger
+
+
+def _level_from_env(value: str | None) -> int:
+    """Map a level name to a logging level constant."""
+    if not value:
+        return logging.INFO
+    try:
+        return getattr(logging, value.upper())
+    except AttributeError:
+        return logging.INFO

src/gitea_runner_manager/report.py

@@ -6,6 +6,7 @@ from collections.abc import Generator
 from contextlib import contextmanager
 
 from .i18n import _
+from .logging_config import get_logger
 
 
 class Step:
@@ -56,14 +57,15 @@ def track_steps() -> Generator[StepTracker, None, None]:
 
 def _print_report(steps: list[Step]) -> None:
     """Print a translated operation report to stdout."""
+    logger = get_logger()
     icons = {
         "completed": "✓",
         "failed": "✗",
         "pending": "○",
         "in_progress": "◌",
     }
-    print(f"[GRM] {_('=== Operation Report ===')}")
+    logger.info(_("=== Operation Report ==="))
     for step in steps:
         icon = icons.get(step.status, "?")
         status_label = _(step.status)
-        print(f"[GRM]   {icon} {step.name} ({status_label})")
+        logger.info(f"  {icon} {step.name} ({status_label})")