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.

src/state.rs

@@ -71,6 +71,8 @@ pub struct AppState {
     pub stats: Arc<Stats>,
     pub promotion: Arc<crate::promotion::Promotion>,
     pub imports: Arc<crate::import::JobStore>,
+    /// Image/video generation jobs (cortiq imagine / animate).
+    pub media: Arc<crate::media::MediaStore>,
     /// Managed local CMF model server (install/update/spawn lifecycle + status).
     pub cmf: Arc<crate::cmf_runtime::CmfRuntime>,
     pub cache: Arc<SemanticCache>,
@@ -113,6 +115,7 @@ impl SharedState {
         let stats = Stats::new(&cfg.stats);
         let promotion = crate::promotion::Promotion::new(promotion_cfg(&cfg.shadow));
         let imports = crate::import::JobStore::new();
+        let media = crate::media::MediaStore::new();
         let cmf = crate::cmf_runtime::CmfRuntime::new();
         let cache = SemanticCache::new(&cfg.cache);
         let router_status = RouterLastStatus::default();
@@ -122,6 +125,7 @@ impl SharedState {
             stats,
             promotion,
             imports,
+            media,
             cmf,
             cache,
             secrets,