Fix Phase 15 header: all sub-phases complete

Author: Zajfan

.planning/ROADMAP.md

@@ -701,11 +701,9 @@ Phantom is an infant today. This phase will happen when it is ready, not before.
 
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-## Phase 15: Creator & Community Economy (v1.4) 🟡 Partially Complete
+## Phase 15: Creator & Community Economy (v1.4) ✅ Complete
 
 > **High priority for engagement and retention.** Builds on existing events, stickers, and bots infrastructure. Addresses Discord Nitro paywalls and creator migration demand.
->
-> Some items (badges, boosts, Canvas) were implemented during earlier phases. Remaining items focus on monetization and discovery.
 
 ### 15-01: Server Supporter Tiers (Boosts) ✅ Complete