feat(M09): introduce RuntimeContext and attach to processing object

- Add modules/runtime_context.py with RuntimeContext dataclass
- Attach p.runtime_context in process_images_inner() after opts_snapshot
- Write-only: no migration of shared.* reads yet
- Completes Phase II runtime seam preparation

Made-with: Cursor

modules/runtime_context.py

@@ -0,0 +1,18 @@
+"""Runtime execution context for generation runs.
+
+M09: Lightweight context grouping model, opts_snapshot, device, state,
+cmd_opts. Attached to processing object as p.runtime_context.
+Write-only in M09; not yet consumed by runtime.
+"""
+from dataclasses import dataclass
+
+
+@dataclass
+class RuntimeContext:
+    """Groups runtime dependencies for the generation pipeline."""
+
+    model: object
+    opts_snapshot: object
+    device: object
+    state: object
+    cmd_opts: object