feat: add Apple Liquid Glass templates, image security settings, and automated releases

## New Features
- Apple Liquid Glass CSS template with iOS 26-inspired design
- Liquid Glass Dark theme with neon accents
- Image Security settings tab with per-event protection levels
- Release Please automation for versioning and changelog

## Improvements
- Update CSS template migration with final working templates
- Add search placeholder visibility fix for glass themes
- Update README roadmap (Download Protection, Gallery Templates, Filtering & Export now implemented)

## Infrastructure
- Add release-please.yml workflow for automated releases
- Add release-please-config.json and manifest
- Update docker-build.yml with Release Please integration comments
- Add comprehensive CHANGELOG.md

## Cleanup
- Add working/planning docs to .gitignore (CLAUDE.md, test-*.md, feature-*.md, etc.)
- Remove internal planning documents from git tracking (kept locally)

## Files Added
- .github/workflows/release-please.yml
- .release-please-manifest.json
- release-please-config.json
- CHANGELOG.md
- frontend/src/features/settings/tabs/ImageSecurityTab.tsx

.github/workflows/docker-build.yml

@@ -1,13 +1,19 @@
 name: Build and Push Docker Images
 
+# This workflow is triggered by:
+# - Push to main/develop branches (builds 'latest' or branch-tagged images)
+# - Version tags from Release Please (e.g., v1.2.0 -> builds versioned images)
+# - GitHub Releases (created by Release Please)
+# - Manual workflow dispatch
+
 on:
   push:
     branches: [ main, develop ]
-    tags: [ 'v*.*.*' ]
+    tags: [ 'v*.*.*' ]  # Triggered by Release Please tags
   pull_request:
     branches: [ main ]
   release:
-    types: [ published ]
+    types: [ published ]  # Triggered when Release Please creates a release
   workflow_dispatch:
     inputs:
       push: