feat: vault-aligned server v1 + UX polish

Redesign the optional FastAPI companion around vault files (manifest /
PUT/GET/DELETE + OCR jobs) instead of legacy strokes_json notes. Wire a
client Server settings panel for health/login. Polish shell UX: l10n for
settings/home/board, sticky-board empty state, and a narrow-screen
diagnostics FAB.

Co-authored-by: Cursor <cursoragent@cursor.com>

lib/l10n/app_en.arb

@@ -199,5 +199,43 @@
   },
   "syncAuto": "Sync automatically on launch",
   "syncCredentialsNote": "Credentials are stored locally in plain text. Use a dedicated app password.",
-  "syncNotConfigured": "Enter a server URL to enable sync."
+  "syncNotConfigured": "Enter a server URL to enable sync.",
+  "settingsDefaults": "Defaults",
+  "settingsAppearance": "Appearance",
+  "settingsAbout": "About",
+  "settingsDefaultTool": "Default tool",
+  "settingsDefaultColor": "Default color",
+  "settingsDefaultWidth": "Default stroke width",
+  "settingsPressureCurve": "Pressure curve",
+  "settingsClearConfirmBody": "This resets pen defaults and appearance. Notes and documents are not affected.",
+  "serverSection": "BadNote Server",
+  "serverUrl": "Server URL",
+  "serverUrlHint": "http://192.168.1.10:8080",
+  "serverUsername": "Username",
+  "serverPassword": "Password",
+  "serverSave": "Save & sign in",
+  "serverTest": "Test connection",
+  "serverTestOk": "Connected · API {version}",
+  "@serverTestOk": {
+    "placeholders": { "version": { "type": "String" } }
+  },
+  "serverTestFail": "Connection failed: {error}",
+  "@serverTestFail": {
+    "placeholders": { "error": { "type": "String" } }
+  },
+  "serverLoggedIn": "Signed in",
+  "serverHint": "Optional. Self-hosted vault assist + deferred OCR; notes stay fully offline.",
+  "boardEmptyTitle": "No sticky notes yet",
+  "boardEmptyBody": "Tap + to add a card. Write [[other-card-id]] in the body to create a backlink.",
+  "relativeJustNow": "Just now",
+  "relativeMinutesAgo": "{n}m ago",
+  "@relativeMinutesAgo": { "placeholders": { "n": { "type": "int" } } },
+  "relativeHoursAgo": "{n}h ago",
+  "@relativeHoursAgo": { "placeholders": { "n": { "type": "int" } } },
+  "relativeYesterday": "Yesterday",
+  "diagExported": "Diagnostic pack exported ({bytes} bytes)\nPath copied",
+  "@diagExported": { "placeholders": { "bytes": { "type": "int" } } },
+  "diagExportFail": "Export failed: {error}",
+  "@diagExportFail": { "placeholders": { "error": { "type": "String" } } },
+  "processingOcr": "Processing OCR…"
 }