feat(ai-moderation): add user profile self-learning system

Add user_profiles table, store, and background learner worker
that summarizes user communication style, topics, and personality.

- New user_profiles table (user_id PK, guild_id, profile_summary, last_analyzed_at)
- userProfileStore.ts — CRUD (get/update) following channelCultureStore pattern
- userProfileLearner.ts — background worker: queries 100 recent msgs per user,
  calls LLM for personality summary, updates every 12h
- Inject <user_profile> XML tag per-message in moderation prompt
- Start worker alongside cultureLearner in aiAnalyzer.ts
- Migration 0008 for user_profiles table

Co-Authored-By: Claude <noreply@anthropic.com>

services/discord-gateway/src/modules/ai-moderation/moderationPrompt.ts

@@ -605,6 +605,10 @@ export interface BuildSystemPromptOptions {
    * Formatted XML block containing the AI-generated channel culture summary.
    */
   channelCulture?: string;
+  /**
+   * Formatted profile summary for the user being moderated.
+   */
+  userProfile?: string;
 }
 
 export function buildSystemPrompt(options: BuildSystemPromptOptions): string {
@@ -615,6 +619,7 @@ export function buildSystemPrompt(options: BuildSystemPromptOptions): string {
     correction,
     correctedExamples,
     channelCulture,
+    userProfile,
   } = options;
 
   // Backward compatibility: if mode is not set but includeMediaInstructions is,
@@ -649,6 +654,11 @@ export function buildSystemPrompt(options: BuildSystemPromptOptions): string {
     parts.push(`## Kultur Channel (Pembelajaran AI)\n${channelCulture}`);
   }
 
+  // User Profile Injection (Learning)
+  if (userProfile) {
+    parts.push(`## Profil Pengirim (Pembelajaran AI)\n${userProfile}`);
+  }
+
   parts.push(
     `## Konteks Pengguna\nSetiap pesan mungkin memiliki tag <user_reputation>. Tag ini hanya indikator **referensi**, bukan bukti pelanggaran. Nilai trust_score yang rendah bukan alasan untuk memflag pesan yang bersih. Nilai trust_score yang tinggi bukan alasan untuk mengabaikan pelanggaran nyata. **Setiap pesan harus dinilai berdasarkan isinya sendiri.**`,
   );