fix: hang the iron cauldron inside the tripod

[TMHSDigital]

Summary

The bulged pot was intersecting the timber poles (TRIPOD_R 0.32 vs ~0.195 m pot radius at the waist). Spread the feet to 0.56 m so the pot hangs in the triangle with a recomputed air gap.

Evidence

Live run on .scratch binaries that report 4.5.11 / 5.1.2 / 5.2.1:

• Default exit 0, argparse 2, --skip-decimate 9 on all three
• Pot–leg clearance (shell verts vs pole axes minus pole radius): 0.0513 m (declared ≥ 0.04; clip exits 3)
• Outer AABB fitted to result: (1.013, 0.986, 0.827) m
• Base tris still 3388; LOD1 0.5000; LOD2 0.2196 / 0.2196 / 0.2172
• Cycles still on 5.2.1; check_framing without deviation=

Inspection only: gallery card alt/witnesses after scripts/build_gallery.py.

Test plan

• needs-5.1 via REST; 5.1 job present
• smoke 4.5 / 5.1 / 5.2 + Validate + Socket green
• Gallery still shows air between pot and poles