refactor: remove unused AI columns from messages table

Drop 3 columns that were written but never read:
- ai_moderation_raw: raw LLM JSON response (~KB per message, never consumed)
- ai_policy_version: hardcoded 'default-2026-05-30', never used for decisions
- ai_evidence: JSON evidence array, never read after write

Changes:
- schema.ts: remove columns from both Postgres and SQLite table definitions
- messageStore.ts: remove from AIAnalysisUpdate interface and SET clauses
- aiAnalyzer.ts: remove from individual fallback update calls
- aiAnalysisWorker.ts: remove raw write, add missing fields (categories, severity, etc.)
- types.ts: remove from MessageRecord interface
- analysisRoutes.ts: remove from reset analysis call
- New migration: src/database/migrations/001_drop_unused_ai_columns.sql
- Migration applied to live DB: 27 columns → 24 columns

Kept ai_error (useful for future debugging, currently 0 non-null)
Kept metadata (1.9MB total, used for AI sticker/embed evidence analysis)

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

src/moderation/aiAnalysisWorker.ts

@@ -103,8 +103,11 @@ export default async function processAnalysisRequest({
         status: analysisResult.status,
         flags: JSON.stringify(analysisResult.flags),
         score: analysisResult.score,
-        raw: JSON.stringify(result.raw),
         analysis: analysisResult.analysis,
+        categories: analysisResult.categories,
+        severity: analysisResult.severity,
+        confidence: analysisResult.confidence,
+        recommendedAction: analysisResult.recommendedAction,
         analyzedAt: Date.now(),
         error: null,
       },

src/moderation/aiAnalyzer.ts

@@ -304,14 +304,11 @@ async function processIndividualFallback(
         status: r.status,
         flags: JSON.stringify(r.flags),
         score: r.score,
-        raw: JSON.stringify(analysisResult.raw),
         analysis: r.analysis,
         categories: r.categories,
         severity: r.severity,
         confidence: r.confidence,
         recommendedAction: r.recommendedAction,
-        policyVersion: r.policyVersion,
-        evidence: r.evidence,
         analyzedAt: Date.now(),
         error: null,
       },
@@ -361,15 +358,12 @@ async function processIndividualFallback(
             status: "error",
             flags: JSON.stringify(["individual_analysis_exhausted"]),
             score: 0,
-            raw: null,
             analysis:
               "Individual fallback exhausted all retries: LLM consistently dropped this message even in single-target mode",
             categories: ["individual_analysis_exhausted"],
             severity: "none",
             confidence: 0,
             recommendedAction: "review",
-            policyVersion: "default-2026-05-30",
-            evidence: [],
             analyzedAt: Date.now(),
             error: lastError,
           },

src/moderation/messageStore.ts

@@ -184,7 +184,6 @@ export async function updateMessageAsEdited(
         ai_status: "pending",
         ai_moderation_flags: null,
         ai_moderation_score: null,
-        ai_moderation_raw: null,
         ai_analysis: null,
         ai_analyzed_at: null,
         ai_error: null,
@@ -392,14 +391,11 @@ interface AIAnalysisUpdate {
   status: "pending" | "clean" | "warn" | "flagged" | "error";
   flags?: string | null;
   score?: number | null;
-  raw?: string | null;
   analysis?: string | null;
   categories?: string[] | string | null;
   severity?: MessageRecord["ai_severity"] | null;
   confidence?: number | null;
   recommendedAction?: MessageRecord["ai_recommended_action"] | null;
-  policyVersion?: string | null;
-  evidence?: string[] | string | null;
   analyzedAt?: number | null;
   error?: string | null;
 }
@@ -423,14 +419,11 @@ export async function updateMessageAIAnalysis(
         ai_status: result.status,
         ai_moderation_flags: result.flags ?? null,
         ai_moderation_score: result.score ?? null,
-        ai_moderation_raw: result.raw ?? null,
         ai_analysis: result.analysis ?? null,
         ai_categories: stringifyAIList(result.categories),
         ai_severity: result.severity ?? null,
         ai_confidence: result.confidence ?? result.score ?? null,
         ai_recommended_action: result.recommendedAction ?? null,
-        ai_policy_version: result.policyVersion ?? null,
-        ai_evidence: stringifyAIList(result.evidence),
         ai_analyzed_at: result.analyzedAt ?? Date.now(),
         ai_error: result.error ?? null,
       })

src/moderation/types.ts

@@ -33,14 +33,11 @@ export interface MessageRecord {
   ai_status?: AIStatus | null;
   ai_moderation_flags?: string | null;
   ai_moderation_score?: number | null;
-  ai_moderation_raw?: string | null;
   ai_analysis?: string | null;
   ai_categories?: string | null;
   ai_severity?: AISeverity | null;
   ai_confidence?: number | null;
   ai_recommended_action?: AIRecommendedAction | null;
-  ai_policy_version?: string | null;
-  ai_evidence?: string | null;
   ai_analyzed_at?: number | null;
   ai_error?: string | null;
 }