fix(assets): purge stale 5-layer/peripheral references from fog spec

Round 3 review fixes — thorough spec cleanup:
- Remove visibility_sectors from data flow (peripheral removed in #569)
- Remove player_pos uniform (cone center implicit in visibility_tex)
- Update FogState pseudocode: remove sector step, add zone tint step
- Update lifecycle diagram to match single update_from_state() call
- Fix "5-layer fog" → "3-state fog" in Files to Create and impl notes
- Mark zone tint open question as resolved (Sprint 22, D-077)
- Document filter_nearest rationale on zone_tint_tex (D-073 hard zones)
- Note low-saturation tint is intentional per D-046 Hopper test

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

client/scripts/autoloads/fog_state.gd

@@ -17,6 +17,8 @@ const EXP_VISIBLE: int = 255    # Currently in LOS — clear (written each frame
 
 # Zone temperature tints (D-059 + D-046, Sprint 22) — keyed by zone_id string from server.
 # Matches audio_manager.gd ZONE_ASSETS zone_id strings for consistent zone semantics.
+# Low saturation is intentional (D-046): tints are subtle — distinguishable as warm/cool/neutral
+# in side-by-side comparison, not garish. The "Hopper test" validates this.
 # Colors are dark tints used as the fog overlay in the deep fog zone:
 #   hub/workplace: #1a1f2e (cool blue-dark — terminal, institutional)
 #   bar:           #2a1f15 (warm amber-dark — social, inhabited)