test(M00): add camera pose sweep

docs/CAMERA_POSE_SWEEP.md

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+# Renderer Camera Pose Sweep
+
+This offline M00 diagnostic recovers reproducible checkpoint framing when an original-client screenshot has no recorded camera yaw or pitch. It ranks a bounded grid; it does not change renderer or player-camera defaults and does not prove the exact build 12340 camera pose without human approval.
+
+## Camera contract
+
+`capture_render_checkpoints.gd` accepts additive `--camera-yaw-offset` and `--camera-pitch-offset` values in degrees. Yaw rotates the no-roll checkpoint basis around Godot world `Vector3.UP`; pitch then rotates around the camera-local right axis. Zero offsets preserve the manifest target exactly. `--single-pass` captures only `cold_process` and is intended for pose calibration, not performance baselines.
+
+## Workflow
+
+```powershell
+.\tools\sweep_render_checkpoint_camera_pose.ps1 `
+  -ReferenceDirectory 'D:\private-fixtures\wow-3.3.5a-checkpoints' `
+  -Checkpoint elwynn_adt_boundary `
+  -YawOffsets -15,-10,-5,0,5,10,15 `
+  -PitchOffsets -10,-5,0,5,10 `
+  -WaitSeconds 2
+```
+
+Each candidate receives its own output directory and comparison report. `ranking.json` sorts candidates by mean perceptual error and then changed-pixel ratio. Use `-PlanOnly` to validate the Cartesian grid and output paths without rendering. Run a coarse grid first, then a finer grid around the best candidate.
+
+```mermaid
+flowchart LR
+    Y[Yaw offsets in degrees] --> G[Bounded Cartesian grid]
+    P[Pitch offsets in degrees] --> G
+    G --> C[Single-pass checkpoint captures]
+    R[Original-client reference] --> D[Perceptual comparator]
+    C --> D
+    D --> J[ranking.json]
+    J --> H[Human framing approval]
+```
+
+## Interpretation and recovery
+
+The smallest error is a candidate, not automatic fidelity approval. Geometry, materials, lighting and FOV can move the perceptual optimum away from the true original-client pose. Inspect the best images manually and retain the original reference outside Git. A missing matching reference or candidate is a hard error; correct the checkpoint filter or filenames and rerun. Generated PNG and JSON outputs are disposable local evidence.
+
+## Verification
+
+The headless capture dry-run must report requested yaw and pitch offsets. Comparator `--self-test` covers paired metrics. Sweep `-PlanOnly` covers deterministic grid expansion and output naming without requiring a display. A real ranked sweep requires a display and a private build 12340 reference image.