fix(plugins): replace dependency marker files with a real satisfaction check

The .dependencies_installed hash-marker system only tracked "was this exact
requirements.txt hashed before" — not whether the packages it names are
actually present. That made it fragile (a wiped venv, a manually removed
package, or a lost/corrupted marker forces a needless full pip reinstall or,
worse, a false skip) and produced dead weight for the ~10 plugins whose
requirements.txt is comment-only (they still paid a pip subprocess on first
boot before a marker existed).

Replace it with requirements_are_satisfied() in plugin_loader.py, which
checks each real requirement line against importlib.metadata directly, so
install_dependencies() only shells out to pip when something is actually
missing or version-mismatched. Drops the marker file entirely: removed all
marker read/write sites in plugin_loader.py and store_manager.py, the
now-pointless marker-cleanup step in the git-update path, the unused legacy
marker implementation in plugin_manager.py, and the already-stale
clear_dependency_markers.sh script.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01KEZK1P1Q1fu5pcuVrkrCFZ

src/plugin_system/plugin_manager.py

@@ -9,7 +9,6 @@ API Version: 1.0.0
 
 import json
 import sys
-import subprocess
 import time
 import threading
 from pathlib import Path
@@ -177,90 +176,6 @@ class PluginManager:
 
         return plugin_ids
 
-    def _get_dependency_marker_path(self, plugin_id: str) -> Path:
-        """Get path to dependency installation marker file."""
-        plugin_dir = self.plugins_dir / plugin_id
-        if not plugin_dir.exists():
-            # Try with ledmatrix- prefix
-            plugin_dir = self.plugins_dir / f"ledmatrix-{plugin_id}"
-        return plugin_dir / ".dependencies_installed"
-
-    def _check_dependencies_installed(self, plugin_id: str) -> bool:
-        """Check if dependencies are already installed for a plugin."""
-        marker_path = self._get_dependency_marker_path(plugin_id)
-        return marker_path.exists()
-
-    def _mark_dependencies_installed(self, plugin_id: str) -> None:
-        """Mark dependencies as installed for a plugin."""
-        marker_path = self._get_dependency_marker_path(plugin_id)
-        try:
-            marker_path.touch()
-            # Set proper file permissions after creating marker
-            from src.common.permission_utils import (
-                ensure_file_permissions,
-                get_plugin_file_mode
-            )
-            ensure_file_permissions(marker_path, get_plugin_file_mode())
-        except (OSError, PermissionError) as e:
-            self.logger.warning("Could not create dependency marker for %s: %s", plugin_id, e)
-
-    def _remove_dependency_marker(self, plugin_id: str) -> None:
-        """Remove dependency installation marker."""
-        marker_path = self._get_dependency_marker_path(plugin_id)
-        try:
-            if marker_path.exists():
-                marker_path.unlink()
-        except (OSError, PermissionError) as e:
-            self.logger.warning("Could not remove dependency marker for %s: %s", plugin_id, e)
-
-    def _install_plugin_dependencies(self, requirements_file: Path) -> bool:
-        """
-        Install plugin dependencies from requirements.txt.
-        
-        Args:
-            requirements_file: Path to requirements.txt
-            
-        Returns:
-            True if installation succeeded or not needed, False on error
-        """
-        try:
-            self.logger.info("Installing dependencies from %s", requirements_file)
-            result = subprocess.run(
-                [sys.executable, "-m", "pip", "install", "--break-system-packages", "--no-cache-dir", "-r", str(requirements_file)],
-                capture_output=True,
-                text=True,
-                timeout=300,
-                check=False
-            )
-            
-            if result.returncode == 0:
-                self.logger.info("Dependencies installed successfully")
-                return True
-            else:
-                self.logger.warning("Dependency installation returned non-zero exit code: %s", result.stderr)
-                return False
-        except subprocess.TimeoutExpired:
-            self.logger.error("Dependency installation timed out")
-            return False
-        except FileNotFoundError as e:
-            self.logger.warning("Command not found: %s. Skipping dependency installation", e)
-            return True
-        except (BrokenPipeError, OSError) as e:
-            # Handle broken pipe errors (errno 32) which can occur during pip downloads
-            # Often caused by network interruptions or output buffer issues
-            if isinstance(e, OSError) and e.errno == 32:
-                self.logger.error(
-                    "Broken pipe error during dependency installation. "
-                    "This usually indicates a network interruption or pip output buffer issue. "
-                    "Try installing again or check your network connection."
-                )
-            else:
-                self.logger.error("OS error during dependency installation: %s", e)
-            return False
-        except Exception as e:
-            self.logger.error("Unexpected error installing dependencies: %s", e, exc_info=True)
-            return True
-
     def load_plugin(self, plugin_id: str) -> bool:
         """
         Load a plugin by ID.