feat: persistent container log collection, unified rotation, logs page redesign

- log_manager: add collect_container_logs (appends docker logs to container_<name>.log),
  get_container_log_lines, rotate_container_log, get_all_log_file_infos
- app.py: new endpoints /api/logs/files (all log file sizes), /api/logs/containers/<name>
  (collect+return stored container logs); rotate endpoint now handles both service and container logs
- Logs page: split into API Service Logs tab (python manager logs) and Container Logs tab
  (persistent docker stdout/stderr); Statistics tab shows both kinds with per-row rotate;
  each tab has a description explaining what it shows and where files live
- wireguard_manager: test_connectivity peer_ip=None guard (already in previous commit, now rebuilt)

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

api/log_manager.py

@@ -498,6 +498,96 @@ class LogManager:
         except Exception as e:
             return {'error': str(e)}
     
+    def collect_container_logs(self, container_name: str, docker_client=None) -> int:
+        """Append new docker container stdout/stderr to a persistent log file.
+        Returns number of new lines written, or -1 on error."""
+        try:
+            import subprocess
+            log_file = self.log_dir / f'container_{container_name}.log'
+            # Determine --since timestamp from last line of existing file
+            since_arg = []
+            if log_file.exists() and log_file.stat().st_size > 0:
+                with open(log_file, 'r', encoding='utf-8', errors='ignore') as f:
+                    for line in f:
+                        pass
+                # Parse last timestamp from docker log line (format: 2006-01-02T15:04:05...)
+                ts_match = re.match(r'^(\d{4}-\d{2}-\d{2}T\d{2}:\d{2}:\d{2}\.\d+Z)', line.strip())
+                if ts_match:
+                    since_arg = ['--since', ts_match.group(1)]
+
+            result = subprocess.run(
+                ['docker', 'logs', '--timestamps'] + since_arg + [container_name],
+                capture_output=True, text=True, timeout=30
+            )
+            output = result.stdout + result.stderr
+            lines = [l for l in output.splitlines() if l.strip()]
+            if lines:
+                with open(log_file, 'a', encoding='utf-8') as f:
+                    f.write('\n'.join(lines) + '\n')
+            return len(lines)
+        except Exception as e:
+            logger.error(f"Error collecting container logs for {container_name}: {e}")
+            return -1
+
+    def get_container_log_lines(self, container_name: str, lines: int = 100) -> List[str]:
+        """Read last N lines from stored container log file."""
+        try:
+            log_file = self.log_dir / f'container_{container_name}.log'
+            if not log_file.exists():
+                return []
+            with open(log_file, 'r', encoding='utf-8', errors='ignore') as f:
+                all_lines = f.readlines()
+            return [l.rstrip() for l in all_lines[-lines:]] if lines > 0 else [l.rstrip() for l in all_lines]
+        except Exception as e:
+            logger.error(f"Error reading container log for {container_name}: {e}")
+            return []
+
+    def rotate_container_log(self, container_name: str):
+        """Rotate a stored container log file."""
+        try:
+            log_file = self.log_dir / f'container_{container_name}.log'
+            if not log_file.exists():
+                return
+            # Find next available backup index
+            for i in range(1, self.backup_count + 1):
+                backup = self.log_dir / f'container_{container_name}.log.{i}'
+                if not backup.exists():
+                    log_file.rename(backup)
+                    logger.info(f"Rotated container log for {container_name} → {backup.name}")
+                    return
+            # All slots full — remove oldest, shift others
+            oldest = self.log_dir / f'container_{container_name}.log.{self.backup_count}'
+            oldest.unlink(missing_ok=True)
+            for i in range(self.backup_count - 1, 0, -1):
+                src = self.log_dir / f'container_{container_name}.log.{i}'
+                if src.exists():
+                    src.rename(self.log_dir / f'container_{container_name}.log.{i + 1}')
+            log_file.rename(self.log_dir / f'container_{container_name}.log.1')
+            logger.info(f"Rotated container log for {container_name}")
+        except Exception as e:
+            logger.error(f"Error rotating container log for {container_name}: {e}")
+
+    def get_all_log_file_infos(self) -> List[Dict[str, Any]]:
+        """Return size/mtime info for all log files (API service logs + container logs)."""
+        results = []
+        for log_file in sorted(self.log_dir.glob('*.log')):
+            try:
+                stat = log_file.stat()
+                name = log_file.stem  # e.g. 'wireguard' or 'container_cell-api'
+                kind = 'container' if name.startswith('container_') else 'service'
+                label = name[len('container_'):] if kind == 'container' else name
+                results.append({
+                    'name': name,
+                    'label': label,
+                    'kind': kind,
+                    'file': log_file.name,
+                    'size': stat.st_size,
+                    'modified': datetime.fromtimestamp(stat.st_mtime).isoformat(),
+                })
+            except Exception:
+                pass
+        return results
+
     def compress_old_logs(self):
         """Compress old log files to save space"""
         try: