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/css/styles.css

@@ -585,6 +585,12 @@ body.modal-open { overflow: hidden; }
 /* Featured gallery: the list grows as new models are published, so give it more
    room than the search grid before it starts scrolling. */
 .featured-section .hf-grid { max-height: min(62vh, 760px); }
+/* Playground media tabs: generated image / video frame */
+.media-out { display: flex; flex-direction: column; gap: 8px; }
+.media-canvas {
+  max-width: 100%; height: auto; border-radius: 8px;
+  border: 1px solid var(--border, #2a2f3a); background: #000;
+}
 /* Live download progress inside a featured card (empty until a job runs) */
 .card-prog:empty { display: none; }
 .card-prog { margin-top: 6px; }