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/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": [