docs: fix documentation inconsistencies (issue #291)

- Fix pact-system-spec.md §5.2: Remove misquote of AGENTS.md (pacts do NOT persist)
- Fix pact-system-spec.md §4.2: Update pactBinding note (now resolved in code)
- Fix pact-system-spec.md §8.2/8.3: Correct floor 140/150/200 element tags
- Add pactInterferenceMitigation to AGENTS.md and GAME_BRIEFING.md (15 upgrades)
- Fix GAME_BRIEFING.md §7: Correct Tier 1 armor values and pact times
- Fix GAME_BRIEFING.md §7: Correct Tier 2 armor values and pact times
- Fix GAME_BRIEFING.md §7: Correct Tier 3 pact times
- Fix GAME_BRIEFING.md §7: Correct floor 100 element (sand, not sand+fire+earth)
- Fix AGENTS.md: Update equipment count from 50 to 43
- Fix AGENTS.md: Fix enchantment design time (per stack, not per effect slot)
- Fix GAME_BRIEFING.md §6: Clarify puzzle room frequency (guaranteed per 7th floor)
- Fix GAME_BRIEFING.md §11: Clarify spireKey formula (1 + level × 2)

docs/specs/attunements/invoker/systems/pact-system-spec.md

@@ -131,9 +131,9 @@ The `pactBinding` prestige upgrade adds +1 slot per level:
 pactSlots: id === 'pactBinding' ? state.pactSlots + 1 : state.pactSlots
 ```
 
-> **Note:** The `pactBinding` upgrade is referenced in the store logic but is **not
-> defined** in `PRESTIGE_DEF` constants. This is a known gap — the upgrade exists
-> in code but has no definition, cost, or max level.
+> **Note:** The `pactBinding` upgrade is defined in `PRESTIGE_DEF` constants
+> (`prestige.ts`) with `max: 5` and `cost: 2000`. It is fully functional in both
+> store logic and UI.
 
 ### 4.3 Slot Enforcement
 
@@ -162,9 +162,9 @@ meaning **pacts do NOT persist through prestige loops**. The player must re-defe
 Guardians and re-sign pacts each loop. The `signedPactDetails` record persists
 for historical tracking but does not confer active boons.
 
-> **Design intent vs. implementation:** The AGENTS.md states "Signed pacts persist
-> through prestige (bounded by `pactSlots`)." The current code resets them. This
-> is a known discrepancy.
+> **Note:** AGENTS.md states "Signed pacts do NOT persist through prestige (reset
+> each loop)." The current code correctly resets `signedPacts` to `[]` on
+> `startNewLoop`, matching the documented behavior. There is no discrepancy.
 
 ---
 
@@ -298,8 +298,8 @@ mana to any elemental type. All elemental mana must come from:
 | 110 | lightning | 22% | 13h |
 | 120 | frost | 28% | 14h |
 | 130 | blackflame | 32% | 15h |
-| 140 | radiantflames | 25% | 16h |
-| 150 | miasma | 28% | 17h |
+| 140 | sand+earth+water | 25% | 16h |
+| 150 | lightning+fire+air | 28% | 17h |
 | 160 | shadowglass | 33% | 18h |
 
 ### 8.3 Tier 3 — Exotic Elements (Floors 170–240)
@@ -309,7 +309,7 @@ mana to any elemental type. All elemental mana must come from:
 | 170 | crystal | 35% | 19h |
 | 180 | stellar | 30% | 20h |
 | 190 | void | 35% | 21h |
-| 200 | soul+stellar+void | 35% | 22h |
+| 200 | crystal+stellar+void | 35% | 22h |
 | 210 | soul+time+plasma | 32% | 23h |
 | 220 | plasma | 28% | 24h |
 | 230 | crystal+stellar+void | 40% | 25h |