balance: improve mid-game crystal income (#165)

Add 150 crystals to shadow_mere and 500 to witch_coven quest rewards.
Double shadow_marshes boss crystal drops (700->1500, 1500->3000, 3000->6000)
to provide meaningful crystal flow for players reaching Shadow Marshes.

apps/api/src/data/bosses.ts

@@ -122,7 +122,7 @@ export const defaultBosses: Array<Boss> = [
   // ── Shadow Marshes ────────────────────────────────────────────────────────
   {
     bountyRunestones: 20,
-    crystalReward:    700,
+    crystalReward:    1500,
     currentHp:        6_000_000,
     damagePerSecond:  1200,
     description:
@@ -140,7 +140,7 @@ export const defaultBosses: Array<Boss> = [
   },
   {
     bountyRunestones: 25,
-    crystalReward:    1500,
+    crystalReward:    3000,
     currentHp:        12_000_000,
     damagePerSecond:  2400,
     description:
@@ -158,7 +158,7 @@ export const defaultBosses: Array<Boss> = [
   },
   {
     bountyRunestones: 30,
-    crystalReward:    3000,
+    crystalReward:    6000,
     currentHp:        20_000_000,
     damagePerSecond:  4000,
     description:

apps/api/src/data/quests.ts

@@ -233,6 +233,7 @@ export const defaultQuests: Array<Quest> = [
     rewards:         [
       { amount: 5_000_000, type: "gold" },
       { amount: 5000, type: "essence" },
+      { amount: 150, type: "crystals" },
       { targetId: "peasant_3", type: "upgrade" },
     ],
     status: "locked",
@@ -249,6 +250,7 @@ export const defaultQuests: Array<Quest> = [
     rewards:         [
       { amount: 20_000_000, type: "gold" },
       { amount: 20_000, type: "essence" },
+      { amount: 500, type: "crystals" },
       { targetId: "shadow_assassin", type: "adventurer" },
     ],
     status: "locked",