feat(playground): image & video generation tabs + real chat metrics

The infosave collection now ships media models (Lumina-Image-2.0, MiniMax-H3
Turbo) that cortiq runs via `imagine`/`animate` CLI, not `cortiq serve`. The
gateway grows a media API: local .cmf files are classified by `cortiq info`
(chat/image/video, cached), generations run as tracked jobs with step progress
parsed from stdout, one at a time, cancellable, outputs under <data>/media.

The playground becomes three tabs. Image: width/height/steps/CFG/seed, live
progress, result rendered from P6 PPM to a canvas in the browser (PNG export
via toBlob). Video: frames/steps/quality/seed plus optional first/last
keyframes (rasterized to PPM client-side); the MJPEG+PCM AVI is decoded in JS
and played on a canvas synced to the wav — no ffmpeg on either side (mp4 remux
happens opportunistically when ffmpeg exists). A metrics card shows resolution,
steps, seed, total time, time per step/frame and file size.

Chat metrics: the local cortiq server sends no usage chunk in streams, so
token counts showed 0/0. tap_stream now injects one OpenAI-shaped usage event
ahead of [DONE] with the gateway's ~4-chars/token estimate, flagged
`cortiq_estimated`; the UI renders it as "≈ N / M" and adds tok/s and
time-to-first-token. Registration skips media packs (a `cortiq serve` entry
for a diffusion model would only fail) in both Register and the wizard's
Finish.

36 new UI strings translated across all 7 languages.

web/js/i18n/fr.js

@@ -468,4 +468,42 @@ export default {
   "onboarding.deleteFile": "Supprimer le fichier .cmf du disque",
   "onboarding.confirmDelete": "Supprimer « {id} » ? Le fichier .cmf sera retiré du disque.",
   "onboarding.unregistered": "Également désenregistré : {ids}",
+
+  // playground: media generation + streaming metrics
+  "pg.tab.chat": "Chat",
+  "pg.tab.image": "Image",
+  "pg.tab.video": "Vidéo",
+  "pg.generate": "Générer",
+  "pg.generating": "Génération…",
+  "pg.genFailed": "Échec de la génération — voir le journal.",
+  "pg.result": "Résultat",
+  "pg.genMetrics": "Métriques de génération",
+  "pg.imagePromptPlaceholder": "un renard roux dans la neige au coucher du soleil, photoréaliste, fourrure détaillée",
+  "pg.videoPromptPlaceholder": "un corgi en toque de chef fait sauter une crêpe, grésillements et aboiement joyeux",
+  "pg.imageEmpty": "L'image générée apparaîtra ici.",
+  "pg.videoEmpty": "Le clip généré (avec le son) apparaîtra ici.",
+  "pg.width": "Largeur",
+  "pg.height": "Hauteur",
+  "pg.steps": "Étapes",
+  "pg.seed": "Seed",
+  "pg.randomSeed": "Seed aléatoire",
+  "pg.cfgHint": "Force du guidance ; ≤ 1 désactive le CFG et divise le travail par deux.",
+  "pg.frames": "Images",
+  "pg.framesHint": "À 24 fps ; arrondi à la grille du modèle.",
+  "pg.quality": "Qualité JPEG",
+  "pg.videoSizeHint": "Multiples de 32 ; le petit côté entraîné est 768.",
+  "pg.videoStepsHint": "La LoRA Turbo est entraînée pour 4 étapes.",
+  "pg.firstFrame": "Première image (optionnel)",
+  "pg.lastFrame": "Dernière image (optionnel)",
+  "pg.keyframeHint": "Transforme la génération en keyframe-to-video.",
+  "pg.resolution": "Résolution",
+  "pg.genTime": "Temps de génération",
+  "pg.timePerStep": "Par étape",
+  "pg.timePerFrame": "Par image",
+  "pg.fileSize": "Taille du fichier",
+  "pg.duration": "Durée",
+  "pg.play": "Lire",
+  "pg.noMediaModels": "Pas encore de modèle {kind} local. Téléchargez-en un (par ex. de la collection infosave) dans Importer :",
+  "pg.tokSpeed": "Vitesse",
+  "pg.ttft": "Premier token",
 };