feat(ai-moderation): introduce user reputation and channel culture context

Implements a context-aware moderation system by tracking user behavior
and channel-specific norms to improve AI decision-making accuracy.

- Adds `user_reputations` table to track trust scores, clean streaks,
  and infraction history.
- Adds `channel_cultures` table to store AI-generated summaries of
  channel-specific norms and slang.
- Implements `userReputationStore` to autonomously update user scores
  based on moderation outcomes (clean vs. flagged).
- Implements `cultureLearner` and `channelCultureStore` to manage
  evolving channel contexts.
- Enhances LLM prompts to inject user reputation (trust scores,
  history) and channel culture summaries, enabling "wisdom-based"
  moderation (e.g., giving benefit of the doubt to high-trust users).
- Integrates reputation and culture updates into the existing
  `aiAnalyzer` pipeline.

services/discord-gateway/src/shared/database/schema.ts

@@ -248,6 +248,45 @@ export const pgVoiceRecordingsTable = pgTable(
   }),
 );
 
+/**
+ * User Reputations Table (PostgreSQL)
+ * Tracks user trust score and infractions to provide context to AI.
+ */
+export const pgUserReputationsTable = pgTable(
+  "user_reputations",
+  {
+    user_id: pgText("user_id").primaryKey(),
+    guild_id: pgText("guild_id").notNull(),
+    trust_score: pgInteger("trust_score").notNull().default(50),
+    clean_message_streak: pgInteger("clean_message_streak").notNull().default(0),
+    total_infractions: pgInteger("total_infractions").notNull().default(0),
+    last_infraction_at: pgBigint("last_infraction_at", { mode: "number" }),
+    created_at: pgBigint("created_at", { mode: "number" }).notNull(),
+    updated_at: pgBigint("updated_at", { mode: "number" }).notNull(),
+  },
+  (table) => ({
+    guildIdx: pgIndex("idx_user_reputations_guild_id").on(table.guild_id),
+    scoreIdx: pgIndex("idx_user_reputations_trust_score").on(table.trust_score),
+  }),
+);
+
+/**
+ * Channel Cultures Table (PostgreSQL)
+ * Stores AI-generated summaries of channel norms and slang to inject as context.
+ */
+export const pgChannelCulturesTable = pgTable(
+  "channel_cultures",
+  {
+    channel_id: pgText("channel_id").primaryKey(),
+    guild_id: pgText("guild_id").notNull(),
+    culture_summary: pgText("culture_summary").notNull(),
+    last_analyzed_at: pgBigint("last_analyzed_at", { mode: "number" }).notNull(),
+  },
+  (table) => ({
+    guildIdx: pgIndex("idx_channel_cultures_guild_id").on(table.guild_id),
+  }),
+);
+
 /**
  * Message Reviews Table (PostgreSQL)
  * Tracks manual reviews of messages flagged by AI moderation
@@ -464,6 +503,8 @@ export const retentionPoliciesTable = pgRetentionPoliciesTable;
 export const textAnalysisCacheTable = pgTextAnalysisCacheTable;
 export const stickerCacheTable = pgStickerCacheTable;
 export const correctedModerationsTable = pgCorrectedModerationsTable;
+export const userReputationsTable = pgUserReputationsTable;
+export const channelCulturesTable = pgChannelCulturesTable;
 
 // Export table types for use in queries
 export type MuxerJob = typeof muxerJobsTable.$inferSelect;
@@ -499,3 +540,9 @@ export type StickerCacheInsert = typeof stickerCacheTable.$inferInsert;
 export type CorrectedModeration = typeof correctedModerationsTable.$inferSelect;
 export type CorrectedModerationInsert =
   typeof correctedModerationsTable.$inferInsert;
+
+export type UserReputation = typeof userReputationsTable.$inferSelect;
+export type UserReputationInsert = typeof userReputationsTable.$inferInsert;
+
+export type ChannelCulture = typeof channelCulturesTable.$inferSelect;
+export type ChannelCultureInsert = typeof channelCulturesTable.$inferInsert;