fix: cap cast progress at 100% after descent completion (bug #381)

Defense-in-depth fix across 2 files:

1. combat-descent-actions.ts: Added castProgress: 0 and weaponCastProgress: {}
   to the isDescentComplete set() call so the meter resets immediately.

2. combat-actions.ts: Added isDescentComplete to the early-exit guard in
   processCombatTick so combat processing stops entirely once descent is
   complete, preventing phantom spell casts from stale castProgress values.

All 1196 tests pass.

docs/circular-deps.txt

@@ -1,5 +1,5 @@
 # Circular Dependencies
-Generated: 2026-06-12T16:57:09.913Z
+Generated: 2026-06-12T17:00:42.616Z
 Found: 4 circular chain(s) — these MUST be fixed before modifying involved files.
 
 1. 1) data/guardian-encounters.ts > data/guardian-procedural.ts

docs/dependency-graph.json

@@ -1,6 +1,6 @@
 {
   "_meta": {
-    "generated": "2026-06-12T16:57:07.675Z",
+    "generated": "2026-06-12T17:00:40.332Z",
     "description": "Import dependency graph for src/lib/game. Keys are files, values are arrays of files they import.",
     "usage": "To find what a file affects, search for its path in the VALUES. To find what a file depends on, look at its KEY entry."
   },

src/lib/game/stores/combat-actions.ts

@@ -95,7 +95,7 @@ export function processCombatTick(
   const logMessages: string[] = [];
   let totalManaGathered = 0;
 
-  if (state.currentAction !== 'climb') {
+  if (state.currentAction !== 'climb' || state.isDescentComplete) {
     return makeDefaultCombatTickResult(rawMana, elements, state, golemancyState.activeGolems);
   }
 

src/lib/game/stores/combat-descent-actions.ts

@@ -52,7 +52,7 @@ export function advanceRoomOrFloor(get: GetFn, set: SetFn): void {
     get().addActivityLog('floor_transition', `Room ${s.currentRoomIndex + 1} passed`);
 
     if (s.currentFloor <= s.exitFloor && s.currentRoomIndex <= 0) {
-      set({ isDescentComplete: true });
+      set({ isDescentComplete: true, castProgress: 0, weaponCastProgress: {} });
       get().addActivityLog('floor_transition',
         'Descent complete — Exit Spire is now available');
       return;