feat(agent): desktop GPU agent container — CCIP + figure crops over HTTP (#114)

The last piece: a Dockerised desktop-GPU worker that talks to FC ONLY over HTTP
(lease → fetch pixels → detect figures + CCIP-embed → submit), so Redis/Postgres
stay private. New top-level agent/ (outside CI scope — verified by running it):
- fc_agent/worker.py: the lease/compute/submit loop, concurrency 1, start/pause/
  stop (stop frees the card; unprocessed leases expire + re-queue).
- fc_agent/models.py: imgutils wrappers — detect_person (figures) + CCIP embed.
  The two API seams to verify against the installed dghs-imgutils (flagged).
- fc_agent/media.py: stills + video frame sampling (ffmpeg) at FC's cadence →
  per-frame instances (the bag).
- fc_agent/crops.py: vendored crop primitive. client.py: the FC HTTP client.
- fc_agent/app.py: FastAPI localhost control UI (start/pause/stop + progress +
  queue depth). Dockerfile (CUDA + onnxruntime-gpu + ffmpeg) + requirements +
  README (token → build → run --gpus all → Start; CPU-fallback path).

This completes the CCIP pipeline end to end: agent produces region CCIP vectors →
RegionService stores → matcher suggests characters → rail. Verified by running on
the desktop (not CI). README calls out the imgutils API + model-string checks.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Ttrj5P7upUTueSfoJcxEqa

agent/fc_agent/config.py

@@ -0,0 +1,26 @@
+"""Agent config, all from env (the control container is configured at run)."""
+import os
+from dataclasses import dataclass
+
+
+@dataclass
+class Config:
+    fc_url: str          # base URL of the FabledCurator web service
+    token: str           # the bearer token from Settings → Tagging → GPU agent
+    agent_id: str        # identifies this agent's leases
+    batch_size: int      # jobs leased per round (concurrency is still 1)
+    ccip_model: str      # imgutils CCIP model name ("" → imgutils default)
+    detector_level: str  # imgutils person-detector level: n|s|m|x
+    poll_idle_seconds: float   # wait between empty leases
+
+    @classmethod
+    def from_env(cls) -> "Config":
+        return cls(
+            fc_url=os.environ.get("FC_URL", "http://localhost:8000").rstrip("/"),
+            token=os.environ.get("FC_TOKEN", ""),
+            agent_id=os.environ.get("AGENT_ID", "desktop-agent"),
+            batch_size=int(os.environ.get("BATCH_SIZE", "4")),
+            ccip_model=os.environ.get("CCIP_MODEL", ""),
+            detector_level=os.environ.get("DETECTOR_LEVEL", "m"),
+            poll_idle_seconds=float(os.environ.get("POLL_IDLE_SECONDS", "10")),
+        )