feat(props): export game boat as iClone staging prop (boat_prop.fbx)

tools/export_boat_prop.py (GLM-implemented, 2 rounds): hull at game scale
(8.5 m, keel 0, no recenter) + placeholder mast/sail/steering oar + 5 seat
markers + waterline + 1.9 m ref figure; self-verify incl. right-side-up
gates added after round 1 shipped an upside-down hull with all checks
green. Registry: boat actions table (6 slots, direct names). README
carries CC BY 4.0 attribution + iClone import/filming notes.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

exchange/outgoing-props/boat/README.md

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+# Boat staging prop — `boat_prop.fbx`
+
+A single static FBX of the ariki-game expedition canoe, rebuilt exactly as
+`ariki-game/src/Viewer/BoatRenderer.cs` assembles it at runtime, for **staging boat-
+interaction character animations in iClone 8**. Built by
+`tools/export_boat_prop.py` (Blender 5.1.2 headless) from
+`ariki-game/assets/models/glbs/Boat__PolynesianCanoe_hull.glb`.
+
+- **Frame:** metres, Z-up, bow = −Y, keel at Z = 0. (Game frame is Y-up, bow = +Z; the
+  tool converts via g2b `(x,y,z) → (x,−z,y)`.)
+- **Scale:** 8.5 m long (`BoatLength`), exported with FBX unit scale = cm → iClone reads
+  it as an **~850 cm** prop with all local scales 1.0.
+- **Generate / re-verify:**
+  `"$BLENDER" --background --python tools/export_boat_prop.py --`
+  (re-runs the export and its built-in self-verify, which must exit 0.)
+
+## Attribution
+
+The hull mesh is the **Polynesian Canoe** by **DITCH.WAV**, licensed **CC BY 4.0**.
+
+- Source: https://sketchfab.com/3d-models/polynesian-canoe-fb4379ba486c43bd846f9b9ef608743a
+- Author: DITCH.WAV — https://sketchfab.com/DITCH.WAV
+- License: CC BY 4.0 — https://creativecommons.org/licenses/by/4.0/
+
+**Modifications made** (required to be noted under CC BY 4.0):
+
+- The game project already removed the baked crab-claw **sail** from the hull GLB
+  (`Boat__PolynesianCanoe_hull.glb` — the `_hull` variant); the carved hull, ama outrigger,
+  and iako booms are unchanged.
+- Rescaled uniformly ×8.5 to the game's `BoatLength` (8.5 m) and re-oriented so the bow
+  runs along the game's +Z (Blender −Y), keel at the waterline.
+- **Staging markers and placeholder rigging added** for iClone authoring only — these are
+  NOT part of the licensed asset: 5 seat-marker spheres, a mast/boom/sail placeholder, a
+  steering-oar placeholder, a waterline outline, and a 1.9 m reference figure. Flat-color
+  materials (no textures) on the added parts; the hull retains its original embedded jpg.
+
+Credit is also given in ariki-game's in-game credits screen and root `ATTRIBUTIONS.md`.
+
+## Contents legend
+
+Every named node in the FBX (positions in **game coords** — Y-up, bow +Z — for reference;
+in the FBX itself they are in Blender Z-up / bow −Y):
+
+| Node | What it is | Game pos (x, y, z) m |
+|---|---|---|
+| `Boat_ArikiCanoe` | The hull mesh (carved canoe + baked ama + iako booms), scaled ×8.5, keel at Z=0. The textured part. | keel at y=0, bow at z=±4.25 |
+| `Mast` | Mast cylinder, radius 0.055, height 4.2 m, centred on the keel at the sail pivot. | (0, deckTop, 0) |
+| `Sail` | Crab-claw sail **placeholder** (silhouette, not accuracy). Foot 2.1 m spreading to **−X** (port), height 3.8 m. | foot at (0, deckTop+0.45, −0.10) |
+| `Boom` | Boom spar along X, radius 0.045, length 2.205 m. | centred (−1.05, deckTop+0.45, −0.10) |
+| `SteeringOar` | Hoe uli (steering oar) placeholder — tapered shaft + blade, raked aft, at the stern starboard oarlock. | pivot (0.384, 0.75, −3.655) |
+| `Seat_Navigator` | Bow seat (4 cm marker). Navigator stands/drives here. | (0, 0.75, +2.55) |
+| `Seat_Lookout` | Mast-top lookout post. | (0, 4.00, −0.20) |
+| `Seat_Fisher` | Port-side seat beside the **ama** outrigger (−X). | (−1.50, 0.65, 0) |
+| `Seat_Rest` | Stern rest seat. | (0, 0.75, −2.975) |
+| `Seat_Helm` | Stern helm by the steering oar — where the pilot stands. | (0.072, 0.50, −2.72) |
+| `Waterline_Fwd/Aft/Stbd/Port` | Four thin edges forming a **10 × 7 m open rectangle** at the still-water surface (Z = −0.06 m). Not a filled plane. | z = −0.06 |
+| `RefFigure_190cm` (+ `_Head`) | 1.9 m capsule reference figure (Ø0.35) standing on `Seat_Helm`, feet at the marker. Scale/height check. | feet at Seat_Helm |
+
+`deckTop` = 0.40 m (computed from the measured hull height as `max(0.12 × height, 0.40)`).
+The ama (outrigger) is baked into the hull on the **port** side (−X), where `Seat_Fisher`
+sits — verified by the hull's centre-of-mass offset.
+
+## iClone import
+
+1. Drag `boat_prop.fbx` into iClone as a **Prop** (Content Manager → drag, or
+   File → Import).
+2. In the **Modify** panel, confirm the prop length is **≈ 850 cm** (8.5 m). If iClone
+   shows ~8.5 cm or ~85 m, the FBX unit preset on import is wrong — re-import with the
+   unit set to **centimeters**.
+3. Drop a CC avatar next to the prop and confirm **`RefFigure_190cm` stands head-high**
+   beside it (~1.9 m). This is your scale ground-truth.
+4. The seat markers (`Seat_*`) are **snap targets** — move/parent hands, feet, hips, and
+   props to them when blocking poses.
+5. When rendering/previewing, **hide `RefFigure_190cm` and the `Waterline_*`** edges
+   (they're staging guides, not part of the scene). The flat-colored placeholder rigging
+   (Mast/Sail/Boom/SteeringOar) is a stand-in — hide or replace it once you have the real
+   rigging; it exists only so blocking reads correctly.
+
+## Filming / authoring notes (per animation)
+
+Jeremy films everything with **Video Mocap**; these notes flag what's filmable vs. what
+needs hand-keying or an ActorCore fallback:
+
+- **Fishing loop** — at `Seat_Fisher` (seated, port side by the ama). Filmable: a stick
+  as the fishing-rod prop. Snap the seated pose onto the marker.
+- **Row / steer loop** — at `Seat_Helm` (stern). Use a broomstick mimicking the stern
+  oar's **±18°** sweep (the game sweeps `4° + effort×14°`, max ±18° under throttle). Film
+  the sweep, then snap the hands to Reach targets on `SteeringOar`/`Seat_Helm` in cleanup.
+- **Collect-flotsam** — kneel/lean over the gunwale (port side). Keep the hands
+  unoccluded in frame (Video Mocap loses occluded joints). Filmable.
+- **Climb-aboard** — film over a **~0.65 m box/table proxy** (the gunwale height). Expect
+  **heavy Reach-target cleanup**; likely a **hand-key fallback** for the final pull-up.
+- **Dive-off** — **airborne motion breaks Video Mocap** (no ground contact, feet leave
+  frame). Film only the **takeoff crouch + spring** and the hand-finish; get the airborne
+  arc from an **ActorCore dive**, or hand-key it.
+- **Sailing sway loops** — gentle stand/brace sway at a seat. **Filmable.** Static bracing
+  poses are hand-posed against the mast/boom.
+
+## Per-take iClone export reminder
+
+For every clip you send back through the animation pipeline:
+
+- **Format:** FBX
+- **Target Tool Preset:** Blender
+- **Frame rate:** 60 fps
+- **Range:** All
+- **Include Motion:** ON (a 2-frame `*TempMotion` take means motion was NOT exported —
+  re-export with this checked)
+- **Preserve Bone Names (CC Base):** ON
+
+Then retarget with `tools/cc_retarget.py` as usual.