Generate Foulborn uniques programmatically from ModFoulbornMap

[EtherealCarnivore]

Summary

Alternative to #9432. Instead of duplicating every unique as static files (+5768 lines), this generates all ~245 Foulborn items programmatically using the existing ModFoulbornMap.lua data and the established pattern in Generated.lua (same approach as Paradoxica, Watcher's Eye, Forbidden Flame/Flesh, etc.).

• Each Foulborn unique becomes a separate generated item (e.g., "Foulborn Alpha's Howl")
• Variants represent different possible Foulborn mutation mods — user picks which mutation via the variant dropdown
• Base mods are copied from the original unique (using "Current" variant for multi-variant items)
• Skin of the Lords uses alt variant to allow selecting both keystone and Foulborn mutation
• Existing item.foulborn detection and threshold counting work without changes

Changes

• src/Modules/Data.lua — Load foulbornMap before Generated.lua runs (1 line)
• src/Data/Uniques/Special/Generated.lua — Foulborn generation loop + buildFoulbornSkinOfTheLords() for the tree-dependent case
• spec/System/TestFoulborn_spec.lua — 9 tests covering generation, parsing, variants, implicits, alt variants

Total: ~370 lines added (vs ~5768 in #9432)

Test plan

• Docker test suite: 204/204 passing (0 failures)
• 9 Foulborn-specific tests covering:
  • Item count (245 generated)
  • Raw text structure (base type, variants, requires, implicits)
  • Item parser integration (foulborn flag, baseName, title, variantList)
  • Multi-variant originals (The Formless Flame → Current variant base)
  • Implicit handling (Call of the Brotherhood)
  • No empty base types across all generated items
  • Skin of the Lords alt variant (keystone + mutation dropdowns)
• Manual GUI testing in PoB (equip items, switch variants, threshold mechanics)

[EtherealCarnivore]

Manual GUI Testing Complete

Tested in PoB on Windows with ~20 items across different categories plus Skin of the Lords:

• Item browser: Foulborn items appear correctly when searching "Foulborn"
• Variant dropdown: Switching between Foulborn mutation variants updates the tooltip and calcs
• Base types: Correct base types for helmets, rings, body armour, etc.
• Implicits: Ring implicits display correctly (e.g., Foulborn Call of the Brotherhood)
• Skin of the Lords: Both dropdowns work — keystone selection + Foulborn mutation selection via alt variant
• Threshold mechanics: Equipping 4+ Foulborn uniques activates threshold bonuses as expected
• No regressions: Non-Foulborn uniques unaffected

Combined with the automated test suite (204/204 passing, 9 Foulborn-specific tests validating all 245 generated items), this covers both structural correctness and runtime behavior.