feat: PWA manifest + the Ghost Log (Workstream C)

manifest.webmanifest referencing the icon assets that actually exist
(sizes verified with file, not asserted), standalone display, no service
worker — offline séance is meaningless and SW cache bugs are not worth it.

GET /api/seances/recent: last 12 sessions in exactly three queries
(sessions+entity join, one GROUP BY for counts, one window-function query
for up to 3 echoes per session). Echoes filter on utterance payload kinds
because DB event kinds carry no greeting/manifest — the agent verified
where _speak actually writes rather than trusting the spec's phrasing.

/log page: entity glyphs, relative in-fiction timestamps, counts, echo
lines in transcript style, gated like the séance, 390px-safe.

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

frontend/src/i18n/es.json

@@ -17,7 +17,34 @@
     "devices": "dispositivos",
     "seance": "sesión",
     "enter": "entrar",
-    "logout": "partir"
+    "logout": "partir",
+    "log": "registro"
+  },
+  "log": {
+    "title": "REGISTRO ESPECTRAL",
+    "subtitle": "cada sesión deja una página tras de sí",
+    "back": "volver a la sesión",
+    "loading": "hojeando el registro hacia atrás…",
+    "error": "el registro no se abre — el velo se resiste esta noche",
+    "empty": "aún no hay sesiones — el registro espera",
+    "noEntity": "nadie respondió",
+    "counts": {
+      "question_one": "{{count}} pregunta",
+      "question_other": "{{count}} preguntas",
+      "anomaly_one": "{{count}} anomalía",
+      "anomaly_other": "{{count}} anomalías",
+      "utterance_one": "{{count}} voz",
+      "utterance_other": "{{count}} voces"
+    },
+    "time": {
+      "moments": "hace instantes",
+      "minutes_one": "hace un minuto",
+      "minutes_other": "hace {{count}} minutos",
+      "hours_one": "hace una hora",
+      "hours_other": "hace {{count}} horas",
+      "days_one": "hace un día",
+      "days_other": "hace {{count}} días"
+    }
   },
   "landing": {
     "taglines": [