docs: overhaul documentation and add four new pages

- Add mining-workflow.md: end-to-end sentence mining guide
- Add anki-integration.md: AnkiConnect setup, field mapping, media generation, field grouping
- Add mpv-plugin.md: chord keybindings, subminer.conf options, script messages
- Add troubleshooting.md: common issues and solutions by category
- Rewrite architecture.md to reflect current ~1,400-line main.ts and ~35 services
- Expand development.md from ~25 lines to full dev guide
- Fix URLs to ksyasuda/SubMiner, version to v0.1.0, AppImage naming
- Update VitePress sidebar with three-group layout (Getting Started, Reference, Development)
- Update navigation in index.md, README.md, docs/README.md
- Remove obsolete planning artifacts (plan.md, investigation.md, comparison.md, composability.md, refactor-main-checklist.md)

docs/.vitepress/config.ts

@@ -24,8 +24,8 @@ export default {
       { text: 'Docs', link: '/' },
       { text: 'Installation', link: '/installation' },
       { text: 'Usage', link: '/usage' },
+      { text: 'Mining', link: '/mining-workflow' },
       { text: 'Configuration', link: '/configuration' },
-      { text: 'Development', link: '/development' },
       { text: 'Architecture', link: '/architecture' },
     ],
     sidebar: [
@@ -35,12 +35,21 @@ export default {
           { text: 'Overview', link: '/' },
           { text: 'Installation', link: '/installation' },
           { text: 'Usage', link: '/usage' },
+          { text: 'Mining Workflow', link: '/mining-workflow' },
         ],
       },
       {
         text: 'Reference',
         items: [
           { text: 'Configuration', link: '/configuration' },
+          { text: 'Anki Integration', link: '/anki-integration' },
+          { text: 'MPV Plugin', link: '/mpv-plugin' },
+          { text: 'Troubleshooting', link: '/troubleshooting' },
+        ],
+      },
+      {
+        text: 'Development',
+        items: [
           { text: 'Development', link: '/development' },
           { text: 'Architecture', link: '/architecture' },
         ],