feat: major platform expansion — Brain service, RSS reader, iOS app, AI assistants, Firefox extension

Brain Service:
- Playwright stealth crawler replacing browserless (og:image, Readability, Reddit JSON API)
- AI classification with tag definitions and folder assignment
- YouTube video download via yt-dlp
- Karakeep migration complete (96 items)
- Taxonomy management (folders with icons/colors, tags)
- Discovery shuffle, sort options, search (Meilisearch + pgvector)
- Item tag/folder editing, card color accents

RSS Reader Service:
- Custom FastAPI reader replacing Miniflux
- Feed management (add/delete/refresh), category support
- Full article extraction via Readability
- Background content fetching for new entries
- Mark all read with confirmation
- Infinite scroll, retention cleanup (30/60 day)
- 17 feeds migrated from Miniflux

iOS App (SwiftUI):
- Native iOS 17+ app with @Observable architecture
- Cookie-based auth, configurable gateway URL
- Dashboard with custom background photo + frosted glass widgets
- Full fitness module (today/templates/goals/food library)
- AI assistant chat (fitness + brain, raw JSON state management)
- 120fps ProMotion support

AI Assistants (Gateway):
- Unified dispatcher with fitness/brain domain detection
- Fitness: natural language food logging, photo analysis, multi-item splitting
- Brain: save/append/update/delete notes, search & answer, undo support
- Madiha user gets fitness-only (brain disabled)

Firefox Extension:
- One-click save to Brain from any page
- Login with platform credentials
- Right-click context menu (save page/link/image)
- Notes field for URL saves
- Signed and published on AMO

Other:
- Reader bookmark button routes to Brain (was Karakeep)
- Fitness food library with "Add" button + add-to-meal popup
- Kindle send file size check (25MB SMTP2GO limit)
- Atelier UI as default (useAtelierShell=true)
- Mobile upload box in nav drawer

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

extensions/brain-firefox/manifest.json

@@ -0,0 +1,49 @@
+{
+  "manifest_version": 3,
+  "name": "Brain - Save to Second Brain",
+  "version": "1.0.0",
+  "description": "One-click save pages, notes, and images to your Second Brain",
+  "permissions": [
+    "activeTab",
+    "contextMenus",
+    "storage",
+    "cookies"
+  ],
+  "host_permissions": [
+    "https://dash.quadjourney.com/*"
+  ],
+  "action": {
+    "default_popup": "popup.html",
+    "default_icon": {
+      "16": "icons/brain-16.png",
+      "32": "icons/brain-32.png",
+      "48": "icons/brain-48.png"
+    }
+  },
+  "background": {
+    "scripts": ["background.js"]
+  },
+  "commands": {
+    "save-page": {
+      "suggested_key": {
+        "default": "Alt+Shift+S"
+      },
+      "description": "Save current page to Brain"
+    }
+  },
+  "icons": {
+    "16": "icons/brain-16.png",
+    "32": "icons/brain-32.png",
+    "48": "icons/brain-48.png",
+    "128": "icons/brain-128.png"
+  },
+  "browser_specific_settings": {
+    "gecko": {
+      "id": "brain@quadjourney.com",
+      "data_collection_permissions": {
+        "required": ["none"],
+        "optional": []
+      }
+    }
+  }
+}