feat: comprehensive balance and bug fix pass (#240)

## Summary

- **fix(#148)**: Boss fights now return a fresh HMAC signature in the response; both the manual and auto-boss paths update `signatureReference` from it, ending the signature-mismatch loop that stopped auto-boss after the first fight
- **fix(#145)**: Militia `baseCost` lowered from 100g → 65g, smoothing the peasant→militia jump from 10× to ~6.5×
- **fix(#144)**: `crystal_shard` buffed from `1.65×/1.2×` → `1.9×/1.3×` — now competitive as an epic trinket
- **fix(#142)**: Click-power recipe progression smoothed across zones 13–18 and ceiling raised: z13 1.20→1.22, z15 1.22→1.25, z17 1.25→1.28, z18 1.28→1.30
- **close(#143)**: `elder_bark_shield` (1.2×), `void_fragment_amulet` (1.15×), and `soul_bound_catalyst` (1.2×) are all already at or above their target values from a prior pass

Closes #148
Closes #145
Closes #144
Closes #142

Reviewed-on: #240
Co-authored-by: Hikari <hikari@nhcarrigan.com>
Co-committed-by: Hikari <hikari@nhcarrigan.com>

apps/api/src/data/adventurers.ts

@@ -21,7 +21,7 @@ export const defaultAdventurers: Array<Adventurer> = [
     unlocked:         true,
   },
   {
-    baseCost:         100,
+    baseCost:         65,
     class:            "warrior",
     combatPower:      3,
     count:            0,

apps/api/src/data/equipment.ts

@@ -269,7 +269,7 @@ export const defaultEquipment: Array<Equipment> = [
     type:     "trinket",
   },
   {
-    bonus: { clickMultiplier: 1.65, goldMultiplier: 1.2 },
+    bonus: { clickMultiplier: 1.9, goldMultiplier: 1.3 },
     description:
       "A fragment of the Mud Kraken's crystallised essence. Focuses raw power into devastating strikes.",
     equipped: false,

apps/api/src/data/recipes.ts

@@ -323,7 +323,7 @@ export const defaultRecipes: Array<CraftingRecipe> = [
 
   // Zone 13: primordial_chaos
   {
-    bonus: { type: "click_power", value: 1.2 },
+    bonus: { type: "click_power", value: 1.22 },
     description:
       "Chaos fragments and creation shards arranged into a lens that hasn't decided what it wants to focus on yet, which somehow makes every click land harder than it should.",
     id:                "chaos_lens",
@@ -387,7 +387,7 @@ export const defaultRecipes: Array<CraftingRecipe> = [
     zoneId: "reality_forge",
   },
   {
-    bonus: { type: "click_power", value: 1.22 },
+    bonus: { type: "click_power", value: 1.25 },
     description:
       "A reality shard carefully shaped with creation tools into something that could, theoretically, become a universe. Instead it makes your clicks unreasonably effective.",
     id:                "universe_seed",
@@ -439,7 +439,7 @@ export const defaultRecipes: Array<CraftingRecipe> = [
     zoneId: "primeval_sanctum",
   },
   {
-    bonus: { type: "click_power", value: 1.25 },
+    bonus: { type: "click_power", value: 1.28 },
     description:
       "The primeval relic, set into a memory shard framework. What function it originally served is unknowable. In your guild's hands, it makes every action more deliberate and more powerful.",
     id:                "first_artefact",
@@ -522,7 +522,7 @@ export const defaultRecipes: Array<CraftingRecipe> = [
 
   // Zone 18: the_absolute
   {
-    bonus: { type: "click_power", value: 1.28 },
+    bonus: { type: "click_power", value: 1.3 },
     description:
       "Absolute fragments ground and set in an omega crystal lattice — an instrument of pure finality. Every action your guild takes through it carries the weight of an ending. It does not miss.",
     id:                "absolute_focus",