fix: assign upgrade rewards to late-game bosses (#140)

Distributes the nine unassigned adventurer-specific upgrade rewards
across Crystalline Spire through Eternal Throne bosses that previously
had empty upgradeRewards arrays, ensuring all adventurer upgrades are
obtainable via boss drops.

apps/api/src/data/bosses.ts

@@ -628,7 +628,7 @@ export const defaultBosses: Array<Boss> = [
     name:                "The Prism Golem",
     prestigeRequirement: 3,
     status:              "locked",
-    upgradeRewards:      [],
+    upgradeRewards:      [ "crystal_sage_1" ],
     zoneId:              "crystalline_spire",
   },
   {
@@ -664,7 +664,7 @@ export const defaultBosses: Array<Boss> = [
     name:                "The Faceted",
     prestigeRequirement: 4,
     status:              "locked",
-    upgradeRewards:      [],
+    upgradeRewards:      [ "void_sentinel_1" ],
     zoneId:              "crystalline_spire",
   },
   {
@@ -682,7 +682,7 @@ export const defaultBosses: Array<Boss> = [
     name:                "The Diamond Colossus",
     prestigeRequirement: 4,
     status:              "locked",
-    upgradeRewards:      [],
+    upgradeRewards:      [ "eternal_champion_1" ],
     zoneId:              "crystalline_spire",
   },
   {
@@ -700,7 +700,7 @@ export const defaultBosses: Array<Boss> = [
     name:                "The Crystal Sovereign",
     prestigeRequirement: 4,
     status:              "locked",
-    upgradeRewards:      [],
+    upgradeRewards:      [ "cosmos_knight_1" ],
     zoneId:              "crystalline_spire",
   },
   // ── Void Sanctum ──────────────────────────────────────────────────────────
@@ -719,7 +719,7 @@ export const defaultBosses: Array<Boss> = [
     name:                "The Void Herald",
     prestigeRequirement: 4,
     status:              "locked",
-    upgradeRewards:      [],
+    upgradeRewards:      [ "seraph_knight_1" ],
     zoneId:              "void_sanctum",
   },
   {
@@ -755,7 +755,7 @@ export const defaultBosses: Array<Boss> = [
     name:                "The Unmaker",
     prestigeRequirement: 5,
     status:              "locked",
-    upgradeRewards:      [],
+    upgradeRewards:      [ "abyss_diver_1" ],
     zoneId:              "void_sanctum",
   },
   {
@@ -791,7 +791,7 @@ export const defaultBosses: Array<Boss> = [
     name:                "The Void Emperor",
     prestigeRequirement: 5,
     status:              "locked",
-    upgradeRewards:      [],
+    upgradeRewards:      [ "infernal_warden_1" ],
     zoneId:              "void_sanctum",
   },
   // ── Eternal Throne ────────────────────────────────────────────────────────
@@ -810,7 +810,7 @@ export const defaultBosses: Array<Boss> = [
     name:                "The Throne Warden",
     prestigeRequirement: 5,
     status:              "locked",
-    upgradeRewards:      [],
+    upgradeRewards:      [ "infinity_ranger_1" ],
     zoneId:              "eternal_throne",
   },
   {
@@ -846,7 +846,7 @@ export const defaultBosses: Array<Boss> = [
     name:                "The Undying",
     prestigeRequirement: 5,
     status:              "locked",
-    upgradeRewards:      [],
+    upgradeRewards:      [ "reality_warden_1" ],
     zoneId:              "eternal_throne",
   },
   {