Add transactional emails (SMTP) and planner features (no-go areas, notes, crash recovery)

Transactional emails:
- Add nodemailer SMTP email module with dev-mode console logging
- Magic link template and welcome template with HTML + plain text
- Wire sendMagicLink into login flow, sendWelcome into registration
- Update privacy page and deploy docs for SMTP configuration

Planner features:
- No-go areas: draw polygons on map (leaflet-geoman), synced via Yjs,
  passed to BRouter as nogos parameter, route recomputes on change
- Session notes: collaborative Y.Text textarea in sidebar tab
- Crash recovery: periodic localStorage save of Yjs state, restore on reconnect
- Rate limit session creation (10/IP/hour) in /new route

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

packages/i18n/src/locales/de.ts

@@ -42,6 +42,19 @@ export default {
       joined: "{{name}} ist beigetreten",
       left: "{{name}} hat die Sitzung verlassen",
     },
+    sidebar: {
+      waypoints: "Wegpunkte",
+      notes: "Notizen",
+    },
+    noGoAreas: {
+      draw: "Sperrgebiet zeichnen",
+      cancel: "Sperrgebiet abbrechen",
+      hint: "Rechtsklick auf ein Sperrgebiet zum Löschen",
+    },
+    notes: {
+      placeholder: "Notizen für diese Sitzung hinzufügen...",
+    },
+    rateLimitExceeded: "Zu viele Anfragen. Bitte versuche es später erneut.",
     elevation: {
       gain: "Höhenmeter aufwärts",
       loss: "Höhenmeter abwärts",

packages/i18n/src/locales/en.ts

@@ -42,6 +42,19 @@ export default {
       joined: "{{name}} joined",
       left: "{{name}} left",
     },
+    sidebar: {
+      waypoints: "Waypoints",
+      notes: "Notes",
+    },
+    noGoAreas: {
+      draw: "Draw no-go area",
+      cancel: "Cancel no-go area",
+      hint: "Right-click a no-go area to delete it",
+    },
+    notes: {
+      placeholder: "Add notes for this session...",
+    },
+    rateLimitExceeded: "Too many requests. Please try again later.",
     elevation: {
       gain: "Elevation Gain",
       loss: "Elevation Loss",