feat: frame QC scoring + viser per-AUV button

Stage 04 frame extract:
- New lib_frame_qc.py: per-frame Laplacian/contrast/blue-dominance scoring
- Classes: bottom_visible / water_no_bottom / turbid_water / out_of_water
- Sample 1/5 frames after extraction, write qc.json per segment
- Record metrics (frames_total, frames_bottom_visible, bottom_visible_pct)
- Mark job degraded when bottom_visible_pct < 50%

Per-AUV viser view:
- scripts/viser_auv.py loads all PLYs of an AUV, color per file
- POST /pipeline/missions/{id}/auvs/{auv}/view rsyncs ply -> worker
- launches viser on hashed port 9300+, returns URL
- _pipeline.html exposes AUV list, JS handler opens viser tab

app/main.py

@@ -320,12 +320,17 @@ async def partial_pipeline(request: Request):
                     counts = {}
                     for j in jobs:
                         counts[j["status"]] = counts.get(j["status"], 0) + 1
+                    auvs: list[str] = []
+                    for j in jobs:
+                        if j["auv_id"] and j["auv_id"] not in auvs:
+                            auvs.append(j["auv_id"])
                     data["missions"].append({
                         "id": m["id"],
                         "name": m["name"],
                         "status": m["status"],
                         "jobs": [dict(j) for j in jobs],
                         "counts": counts,
+                        "auvs": auvs,
                     })
         except Exception as e:
             data["error"] = str(e)[:200]
@@ -571,6 +576,86 @@ async def live_job(job_id: int):
     return {"url": row["viser_url"]}
 
 
+VISER_AUV_BASE = 9300
+PIPELINE_DATA_BASE = Path(os.environ.get("COSMA_PIPELINE_DATA", "/cosma-pipeline/data"))
+
+
+@app.post("/pipeline/missions/{mission_id}/auvs/{auv_id}/view")
+async def view_auv(mission_id: int, auv_id: str):
+    """Launch viser showing all PLYs for one AUV from a mission."""
+    if not PIPELINE_DB.exists():
+        raise HTTPException(404, "state.db introuvable")
+    import hashlib
+    import shutil
+    import tempfile
+
+    with tempfile.NamedTemporaryFile(suffix=".db", delete=False) as tmp:
+        tmp_path = tmp.name
+    shutil.copy2(str(PIPELINE_DB), tmp_path)
+    try:
+        with sqlite3.connect(tmp_path) as conn:
+            conn.row_factory = sqlite3.Row
+            m = conn.execute(
+                "SELECT name FROM missions WHERE id=?", (mission_id,)
+            ).fetchone()
+    finally:
+        try:
+            os.unlink(tmp_path)
+        except Exception:
+            pass
+    if not m:
+        raise HTTPException(404, "mission introuvable")
+    mission_name = m["name"]
+    ply_dir_local = PIPELINE_DATA_BASE / mission_name / "ply" / auv_id
+    if not ply_dir_local.exists():
+        return JSONResponse(
+            {"ok": False, "error": f"PLY dir {ply_dir_local} pas encore (stitch pas done)"},
+            status_code=409,
+        )
+
+    h = int(hashlib.md5(f"{mission_id}-{auv_id}".encode()).hexdigest()[:6], 16)
+    port = VISER_AUV_BASE + (h % 100)
+    worker = WORKERS[1] if len(WORKERS) > 1 else WORKERS[0]
+    alias = worker["ssh_alias"]
+    host = worker["host"]
+    worker_dir = f"/tmp/cosma-viser-auv/{mission_name}/{auv_id}"
+
+    rsync = await asyncio.create_subprocess_exec(
+        "rsync", "-az", "--delete",
+        "-e", "ssh -o BatchMode=yes -o StrictHostKeyChecking=no",
+        f"{ply_dir_local}/", f"{alias}:{worker_dir}/",
+        stdout=asyncio.subprocess.DEVNULL, stderr=asyncio.subprocess.PIPE,
+    )
+    _, err = await rsync.communicate()
+    if rsync.returncode != 0:
+        raise HTTPException(500, f"rsync failed: {err.decode()[:200]}")
+
+    local_script = Path(__file__).parent.parent / "scripts" / "viser_auv.py"
+    scp = await asyncio.create_subprocess_exec(
+        "scp", "-o", "BatchMode=yes", "-o", "StrictHostKeyChecking=no",
+        str(local_script), f"{alias}:/tmp/viser_auv.py",
+        stdout=asyncio.subprocess.DEVNULL, stderr=asyncio.subprocess.PIPE,
+    )
+    _, err = await scp.communicate()
+    if scp.returncode != 0:
+        raise HTTPException(500, f"scp failed: {err.decode()[:200]}")
+
+    venv_py = f"{worker.get('lingbot_path', '/root/ai-video/lingbot-map')}/.venv/bin/python"
+    launch_cmd = (
+        f"pkill -f 'viser_auv.py.*--port {port}' 2>/dev/null ; sleep 1 ; "
+        f"setsid nohup {venv_py} /tmp/viser_auv.py --ply-dir {worker_dir} --port {port} "
+        f"</dev/null >/tmp/viser_auv_{port}.log 2>&1 & disown ; sleep 0.3"
+    )
+    launch = await asyncio.create_subprocess_exec(
+        "ssh", "-o", "BatchMode=yes", "-o", "StrictHostKeyChecking=no", alias, launch_cmd,
+        stdout=asyncio.subprocess.DEVNULL, stderr=asyncio.subprocess.PIPE,
+    )
+    await launch.communicate()
+    await asyncio.sleep(4)
+
+    return {"ok": True, "url": f"http://{host}:{port}/", "auv_id": auv_id, "port": port}
+
+
 @app.post("/stitches/{stitch_id}/view")
 async def view_stitch(stitch_id: int):
     with closing(db()) as conn: