fix: Apply pact affinity cast speed bonus to all spell casts (AC-13)

Previously the pact affinity cast speed bonus was only applied to invocation
spells. Per spec §6.2 and §10.2, it should apply to ALL spell casts (active,
equipment, and invocation).

Changes:
- invocation-utils.ts: Added computeAttackSpeedMultFromPactAffinity() helper
  that combines prestige upgrade + discipline bonus and applies the diminishing
  returns formula
- gameStore.ts: Compute total pact affinity (prestige + discipline) and apply
  cast speed bonus to attackSpeedMult passed to processCombatTick
- combat-actions.ts: Use attackSpeedMult directly for active/equipment spell cast
  progress (bonus already baked in)
- combat-invocation.ts: Use attackSpeedMult directly for invocation cast progress
  (bonus already baked in), removed redundant pactAffinity parameter

docs/circular-deps.txt

@@ -1,5 +1,5 @@
 # Circular Dependencies
-Generated: 2026-06-13T11:02:39.214Z
+Generated: 2026-06-13T11:42:23.525Z
 Found: 4 circular chain(s) — these MUST be fixed before modifying involved files.
 
 1. 1) data/guardian-encounters.ts > data/guardian-procedural.ts