Field banter design doc lands; element wheel and Olija's school corrected in the docs

Field-banter design doc. The doc spells out the five trigger categories, the element / same-target pair / same-target trio / character-solo cascade, the three-bark-per-turn cap, the six-fight dedup window per pool, the replay-safe server-side selection model, the allBanter.json schema, and a plan for an authoring sim that reports where banter would go silent.

Element wheel restated. The design doc described an older version of the element model; the shipped game uses 5+3 — five classic elements with Metal in the ring, plus three esoteric schools where Order is the future-content school. Doc now matches data.

Crafting rule corrected. The doc described a uniform crafting rule that didn't match the shipped table. Updated: own-school materials for T1–T4 area, all strength, and all effect spells; generating-neighbour material is what T5/T6 area spells call for. Same rule the game has been running on; the doc is no longer lying about it.

Olija's school is Order, not Light. The hero plan and Act 4 narrative docs called Olija's school Light; the esoteric set is Order → Fate → Chaos, and Olija anchors Order. Files renamed and references updated.