Add /contacts and /calendar pages; email signature settings; v1.1.12

- /contacts: standalone page with hybrid contact list (submissions + manual entry), inline edit, search, archive
- /calendar: monthly release scheduling calendar reading/writing podcast checklist episode dates
- /email settings: editable signature panel; signature persisted server-side and injected into outgoing emails
- Move contacts out of /admin panel (now links to /contacts route)
- Partial PATCH for contact submissions (name, notes, archived independently)

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

server/data.js

@@ -30,6 +30,7 @@ import {
   DOWNLOAD_COUNTS_FILE,
   EPISODE_PLAYS_FILE,
   ANALYTICS_EVENTS_FILE,
+  EMAIL_SETTINGS_FILE,
   EMPTY_HIT_STATS,
   EMPTY_VISITOR_STATS,
   DEFAULT_REPLY_TEMPLATES,
@@ -385,6 +386,36 @@ export function loadReplyHistoryFromDisk() {
     })
 }
 
+// ── Email settings ────────────────────────────────────────────────────────
+
+export function queueEmailSettingsWrite() {
+  state.emailSettingsWritePromise = state.emailSettingsWritePromise
+    .then(async () => {
+      await mkdir(DATA_DIR, { recursive: true })
+      await writeFile(
+        EMAIL_SETTINGS_FILE,
+        JSON.stringify({ settings: state.emailSettings, updatedAt: new Date().toISOString() }, null, 2),
+        'utf8',
+      )
+    })
+    .catch(err => {
+      console.error('[email-settings] failed to write settings:', err)
+    })
+}
+
+export function loadEmailSettingsFromDisk() {
+  return readFile(EMAIL_SETTINGS_FILE, 'utf8')
+    .then(raw => {
+      const parsed = JSON.parse(raw)
+      if (parsed?.settings && typeof parsed.settings === 'object') {
+        state.emailSettings = { ...state.emailSettings, ...parsed.settings }
+      }
+    })
+    .catch(() => {
+      // Keep defaults from state initializer
+    })
+}
+
 // ── Podcast checklist ──────────────────────────────────────────────────────
 
 export function queuePodcastChecklistWrite() {