feat: replace corrections/tuner with dashboard module

Replace the corrections/adaptive-prompt-tuner feature with a new
dashboard module providing server stats and user profile overview.

Backend:
- Add dashboard module (routes, service, repository) with stats + user list + user detail endpoints
- Remove corrections module entirely
- Wire dashboard router in app.ts

Frontend:
- Add dashboard feature (DashboardStats, UserSummaryList, UserProfileDetail components + useDashboard hook)
- Remove tuner feature (CorrectionStats, CorrectionHistory, SubmitCorrection, useCorrections)
- Update API client from corrections → dashboard types/fns
- Rename tab 'tuner' → 'dashboard'
- Update MobileTabBar, Header, Sidebar links

Tests:
- Expand backend placeholder test with dashboard assertions
- Expand discord-gateway placeholder test with config/channel assertions

AI moderation:
- llmModerationClient: improve status/reply detection, expand safety categories, fix timer reset
- userProfileLearner: fix isReply refinement
- userProfileStore: add pending cache check
- messageMetadata: add crosspost type mapping
- migrate.ts: improve partial-index safety in schema push

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

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

@@ -170,9 +170,20 @@ export async function runMigrations(): Promise<void> {
           const originalQuery = client.query;
           client.query = (async (...args: any[]) => {
             const queryText = args[0];
-            const text = typeof queryText === "string" ? queryText : queryText?.text;
-            if (text && typeof text === "string" && text.includes('CREATE SCHEMA IF NOT EXISTS "public"')) {
-              return { rows: [], command: "CREATE", rowCount: 0, oid: 0, fields: [] };
+            const text =
+              typeof queryText === "string" ? queryText : queryText?.text;
+            if (
+              text &&
+              typeof text === "string" &&
+              text.includes('CREATE SCHEMA IF NOT EXISTS "public"')
+            ) {
+              return {
+                rows: [],
+                command: "CREATE",
+                rowCount: 0,
+                oid: 0,
+                fields: [],
+              };
             }
             return Function.prototype.apply.call(originalQuery, client, args);
           }) as typeof client.query;