feat(paladin): Milestone M6 — 1.13c Paladin assets packaging & metadata registry
- Update scripts/pack-missiles.ts with Paladin missiles (fistoftheheavensbolt, foa, blessedhammerex, blood1) with trans: 1 and dark border suppression max(r,g,b) <= 4 -> alpha = 0.
- Update scripts/pack-overlays.ts with 16 Paladin combat, cast, hit, and state overlays (charge, conversion, conversioncast, holy_bolt_cast, fist_of_the_heavens_cast, handofgod, sanctuary_knockback, holy_fire_hit, holy_fire_indicate, thorns_hit, thorns_indicate, cast_resistfire, cast_resistcold, cast_resistlight, cast_resistall, stun) with preDraw flags and trans: 3 dark halo thresholding.
- Bake and mirror assets across public/ and samples/d2-packs/.
- Generate compile-time metadata in src/render/missiles-meta.ts and src/render/overlays-meta.ts with zero runtime MPQ invariant.
- Add comprehensive unit tests in tests/skills/pal/pal-assets.test.ts.
- Add adversarial coverage audit tests in tests/skills/pal/adv-pal-assets-audit.test.ts.
- Resolves Gitea issue #445.