M8: GUI polish, n8n workflow-3 fixes, RAGcore retrieval root-cause and fix

GUI: dashboard Attention Queue presents a curated severity mix instead of pure
severity-sort (grouped Now/Today/Later headers); Today's Movements seed data
curated so a fresh reset shows a credible day (2+ departures, 2+ returns), with
a new seed-integrity test; About Demo restructured into a compact grid with
progressive disclosure for technical sections; Duplicate Merge shows match/conflict
counts, hides matching fields by default, and previews the final merged record
before confirmation.

Repo hygiene: removed a stray empty `backend;C` directory and an untracked 31MB
zip export; `.gitignore` now excludes future archive exports.

n8n: fixed invalid JSON (a missing `},` between two node objects) in the committed
`fleet-ops-vehicle-return.json` -- the file could not be parsed. Live-validated
workflow 3 (RAGcore Procedure Sync): found and fixed a real defect (three body
parameters had a stray trailing `}}`) and a missing Error Workflow wiring, both
via the safe `n8n import:workflow` CLI path; exported the corrected, still-
inactive workflow as the new source of truth and updated MANIFEST.md/check_drift.py.
Publishing it (starts real daily unattended runs) remains a separate decision.

RAGcore: root-caused and fixed (live, approved) the "zero retrieval candidates"
bug -- a filesystem permission bug (`embedding_profiles.json` unreadable by the
app's own runtime user) that broke every retrieval call before it reached Qdrant.
Every other suspect (grants, scope resolution, Qdrant filters, embeddings) was
verified healthy first. Found a second, deeper gap: the reranker adapter calls
an Ollama HTTP route that does not exist on the deployed Ollama version, so
`/v1/answers` still returns `not_answerable`. `KNOWLEDGE_PROVIDER` stays `demo`
until that is resolved on the RAGcore side. Evidence-based MCP Hub integration
status (real tool-call audit history, not just a boolean flag) replaces the old
`configured`/`not_configured` guess. Full findings in
`docs/final-integrations/current-state-audit.md`.

Backend: 172 tests passing, ruff clean, mypy clean (50 files). Frontend: tsc
clean, production build clean.

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

frontend/src/i18n/locales/fr-BE/dashboard.json

@@ -43,6 +43,9 @@
     "severityMedium": "Avertissement",
     "severityLow": "Info",
     "severityAriaLabel": "Gravité",
+    "tierNow": "À traiter maintenant",
+    "tierToday": "À suivre aujourd'hui",
+    "tierLater": "À contrôler plus tard",
     "empty": "Aucun problème ne correspond à ce filtre.",
     "openRecord": "Ouvrir {{title}}"
   },

frontend/src/i18n/locales/fr-BE/quality.json

@@ -118,6 +118,10 @@
       "keepAsSurvivor": "Conserver comme fiche principale",
       "differs": "Diffère",
       "match": "Identique",
+      "summaryCounts": "{{matchCount}} champs identiques · {{conflictCount}} champs en conflit",
+      "showMatchingFields": "Afficher aussi les champs identiques",
+      "hideMatchingFields": "Masquer les champs identiques",
+      "previewTitle": "Aperçu de la fiche fusionnée ({{ref}})",
       "mergePreview": "{{loser}} deviendra une fiche archivée liée à {{survivor}} ; ses réservations seront transférées.",
       "mergeInto": "Fusionner avec {{ref}}",
       "confirmMergeTitle": "Confirmer la fusion",