feat: add dev preview server and CLI render script (#264)

* fix(web): wire up "Check & Update All" plugins button

window.updateAllPlugins was never assigned, so the button always showed
"Bulk update handler unavailable." Wire it to PluginInstallManager.updateAll(),
add per-plugin progress feedback in the button text, show a summary
notification on completion, and skip redundant plugin list reloads.

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

* feat: add dev preview server, CLI render script, and visual test display manager

Adds local development tools for rapid plugin iteration without deploying to RPi:

- VisualTestDisplayManager: renders real pixels via PIL (same fonts/interface as production)
- Dev preview server (Flask): interactive web UI with plugin picker, auto-generated config
  forms, zoom/grid controls, and mock data support for API-dependent plugins
- CLI render script: render any plugin to PNG for AI-assisted visual feedback loops
- Updated test runner and conftest to auto-detect plugin-repos/ directory

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

* fix(dev-preview): address code review issues

- Use get_logger() from src.logging_config instead of logging.getLogger()
  in visual_display_manager.py to match project logging conventions
- Eliminate duplicate public/private weather draw methods — public draw_sun/
  draw_cloud/draw_rain/draw_snow now delegate to the private _draw_* variants
  so plugins get consistent pixel output in tests vs production
- Default install_deps=False in dev_server.py and render_plugin.py — dev
  scripts don't need to run pip install; developers are expected to have
  plugin deps installed in their venv already
- Guard plugins_dir fixture against PermissionError during directory iteration
- Fix PluginInstallManager.updateAll() to fall back to window.installedPlugins
  when PluginStateManager.installedPlugins is empty (plugins_manager.js
  populates window.installedPlugins independently of PluginStateManager)
- Remove 5 debug console.log statements from plugins_manager.js button setup
  and initialization code

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

* fix(scroll): fix scroll completion to prevent multi-pass wrapping

Change required_total_distance from total_scroll_width + display_width to
total_scroll_width alone. The scrolling image already contains display_width
pixels of blank initial padding, so reaching total_scroll_width means all
content has scrolled off-screen. The extra display_width term was causing
1-2+ unnecessary wrap-arounds, making the same games appear multiple times
and producing a black flicker between passes.

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

* fix(dev-preview): address PR #264 code review findings

- docs/DEV_PREVIEW.md: add bash language tag to fenced code block
- scripts/dev_server.py: add MAX/MIN_WIDTH/HEIGHT constants and validate
  width/height in render endpoint; add structured logger calls to
  discover_plugins (missing dirs, hidden entries, missing manifest,
  JSON/OS errors, duplicate ids); add type annotations to all helpers
- scripts/render_plugin.py: add MIN/MAX_DIMENSION validation after
  parse_args; replace prints with get_logger() calls; narrow broad
  Exception catches to ImportError/OSError/ValueError in plugin load
  block; add type annotations to all helpers and main(); rename unused
  module binding to _module
- scripts/run_plugin_tests.py: wrap plugins_path.iterdir() in
  try/except PermissionError with fallback to plugin-repos/
- scripts/templates/dev_preview.html: replace non-focusable div toggles
  with button role="switch" + aria-checked; add keyboard handlers
  (Enter/Space); sync aria-checked in toggleGrid/toggleAutoRefresh
- src/common/scroll_helper.py: early-guard zero total_scroll_width to
  keep scroll_position at 0 and skip completion/wrap logic
- src/plugin_system/testing/visual_display_manager.py: forward color
  arg in draw_cloud -> _draw_cloud; add color param to _draw_cloud;
  restore _scrolling_state in reset(); narrow broad Exception catches in
  _load_fonts to FileNotFoundError/OSError/ImportError; add explicit
  type annotations to draw_text
- test/plugins/test_visual_rendering.py: use context manager for
  Image.open in test_save_snapshot
- test/plugins/conftest.py: add return type hints to all fixtures

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

* chore: add bandit and gitleaks pre-commit hooks

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

---------

Co-authored-by: Chuck <chuck@example.com>
Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>

scripts/run_plugin_tests.py

@@ -142,8 +142,8 @@ def main():
     """Main entry point."""
     parser = argparse.ArgumentParser(description='Run LEDMatrix plugin tests')
     parser.add_argument('--plugin', '-p', help='Test specific plugin ID')
-    parser.add_argument('--plugins-dir', '-d', default='plugins', 
-                       help='Plugins directory (default: plugins)')
+    parser.add_argument('--plugins-dir', '-d', default=None,
+                       help='Plugins directory (default: auto-detect plugins/ or plugin-repos/)')
     parser.add_argument('--runner', '-r', choices=['unittest', 'pytest', 'auto'],
                        default='auto', help='Test runner to use (default: auto)')
     parser.add_argument('--verbose', '-v', action='store_true',
@@ -153,7 +153,27 @@ def main():
     
     args = parser.parse_args()
     
-    plugins_dir = Path(args.plugins_dir)
+    if args.plugins_dir:
+        plugins_dir = Path(args.plugins_dir)
+    else:
+        # Auto-detect: prefer plugins/ if it has content, then plugin-repos/
+        plugins_path = PROJECT_ROOT / 'plugins'
+        plugin_repos_path = PROJECT_ROOT / 'plugin-repos'
+        try:
+            has_plugins = plugins_path.exists() and any(
+                p for p in plugins_path.iterdir()
+                if p.is_dir() and not p.name.startswith('.')
+            )
+        except PermissionError:
+            print(f"Warning: cannot read {plugins_path}, falling back to plugin-repos/")
+            has_plugins = False
+        if has_plugins:
+            plugins_dir = plugins_path
+        elif plugin_repos_path.exists():
+            plugins_dir = plugin_repos_path
+        else:
+            plugins_dir = plugins_path
+
     if not plugins_dir.exists():
         print(f"Error: Plugins directory not found: {plugins_dir}")
         return 1