Add long-form article editor (NIP-23)

- ArticleEditor with title, markdown body, summary, cover image, tags
- write/preview toggle with markdown rendering via marked
- Auto-save draft to localStorage
- Publish as kind 30023 with NIP-23 tags (d, title, published_at, etc.)
- 'write article' button in sidebar when logged in
- Article preview prose styles in CSS

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

package-lock.json

@@ -12,6 +12,7 @@
         "@tailwindcss/vite": "^4.2.1",
         "@tauri-apps/api": "^2",
         "@tauri-apps/plugin-opener": "^2",
+        "marked": "^17.0.4",
         "react": "^19.1.0",
         "react-dom": "^19.1.0",
         "tailwindcss": "^4.2.1",
@@ -19,6 +20,7 @@
       },
       "devDependencies": {
         "@tauri-apps/cli": "^2",
+        "@types/marked": "^5.0.2",
         "@types/react": "^19.1.8",
         "@types/react-dom": "^19.1.6",
         "@vitejs/plugin-react": "^4.6.0",
@@ -1924,6 +1926,13 @@
         "@types/unist": "*"
       }
     },
+    "node_modules/@types/marked": {
+      "version": "5.0.2",
+      "resolved": "https://registry.npmjs.org/@types/marked/-/marked-5.0.2.tgz",
+      "integrity": "sha512-OucS4KMHhFzhz27KxmWg7J+kIYqyqoW5kdIEI319hqARQQUTqhao3M/F+uFnDXD0Rg72iDDZxZNxq5gvctmLlg==",
+      "dev": true,
+      "license": "MIT"
+    },
     "node_modules/@types/mdast": {
       "version": "4.0.4",
       "resolved": "https://registry.npmjs.org/@types/mdast/-/mdast-4.0.4.tgz",
@@ -2727,6 +2736,18 @@
         "@jridgewell/sourcemap-codec": "^1.5.5"
       }
     },
+    "node_modules/marked": {
+      "version": "17.0.4",
+      "resolved": "https://registry.npmjs.org/marked/-/marked-17.0.4.tgz",
+      "integrity": "sha512-NOmVMM+KAokHMvjWmC5N/ZOvgmSWuqJB8FoYI019j4ogb/PeRMKoKIjReZ2w3376kkA8dSJIP8uD993Kxc0iRQ==",
+      "license": "MIT",
+      "bin": {
+        "marked": "bin/marked.js"
+      },
+      "engines": {
+        "node": ">= 20"
+      }
+    },
     "node_modules/mdast-util-to-hast": {
       "version": "13.2.1",
       "resolved": "https://registry.npmjs.org/mdast-util-to-hast/-/mdast-util-to-hast-13.2.1.tgz",