feat: presence beyond the tab — PWA manifest and the Ghost Log recap

Usability wave Workstream C (#5, #7):
- manifest.webmanifest with existing 192/512/180 icons, linked in
  index.html with theme-color aligned to #07070d; no service worker.
- GET /api/seances/recent: last 12 of the seeker's own séances with
  entity, per-kind event counts (one GROUP BY) and up to 3 spirit
  echoes (one windowed query) — no per-session N+1.
- /log Ghost Log page: cards with GhostGlyph, relative in-fiction
  timestamps, counts and echo lines; LOG link in the séance topbar;
  en/es i18n parity.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

frontend/src/i18n/en.json

@@ -17,7 +17,34 @@
     "devices": "devices",
     "seance": "séance",
     "enter": "enter",
-    "logout": "depart"
+    "logout": "depart",
+    "log": "log"
+  },
+  "log": {
+    "title": "GHOST LOG",
+    "subtitle": "every séance leaves a page behind",
+    "back": "return to the séance",
+    "loading": "leafing back through the log…",
+    "error": "the log will not open — the veil resists tonight",
+    "empty": "no séances yet — the log waits",
+    "noEntity": "no one answered",
+    "counts": {
+      "question_one": "{{count}} question",
+      "question_other": "{{count}} questions",
+      "anomaly_one": "{{count}} anomaly",
+      "anomaly_other": "{{count}} anomalies",
+      "utterance_one": "{{count}} utterance",
+      "utterance_other": "{{count}} utterances"
+    },
+    "time": {
+      "moments": "moments past",
+      "minutes_one": "a minute past",
+      "minutes_other": "{{count}} minutes past",
+      "hours_one": "an hour past",
+      "hours_other": "{{count}} hours past",
+      "days_one": "a day past",
+      "days_other": "{{count}} days past"
+    }
   },
   "landing": {
     "taglines": [