fix(users): drop dead user_reputations JOIN that broke Members page + audit

Root cause: gateway migration 0016 removed the per-user reputation feature
(DROP TABLE user_reputations), but the backend still LEFT JOINed
pgUserReputationsTable in dashboard listUsers/getUserDetail and the chatbot
get_user_reputation tool. Against the live DB these queries raised 42P01
(undefined_table) -> the new /users page could never load (oRPC WS error).

Fix:
- dashboard.repository.ts: remove reputation columns/join from listUsers and
  getUserDetail (data sourced only from messages + user_profiles).
- chatbot.tools.ts: get_user_reputation now returns honest 'unavailable'
  (feature removed) instead of querying the dropped table.
- chatbot.toolDefs.ts: update tool description so the LLM doesn't advertise
  a dead feature.
- frontend types/users view: drop trust_score/clean_message_streak/
  total_infractions/last_infraction_at; derive risk label from real flagged%
  and add warn_count to the inspector (real available data).

Verified: backend+frontend tsc clean, biome clean, 37 unit tests pass,
query tested against live DB (returns real members), build green.

services/backend/src/modules/dashboard/dashboard.repository.ts

@@ -5,7 +5,6 @@ import {
   pgChannelCulturesTable,
   pgMessagesTable,
   pgUserProfilesTable,
-  pgUserReputationsTable,
   pgVoiceRecordingsTable,
 } from "../../shared/index.js";
 import type { ListUsersQuery } from "./dashboard.service.js";
@@ -154,10 +153,6 @@ export class DashboardRepository {
         m.username,
         m.avatar_url,
         p.profile_summary,
-        r.trust_score,
-        r.clean_message_streak,
-        r.total_infractions,
-        r.last_infraction_at,
         m.total_messages,
         m.flagged_count,
         m.clean_count,
@@ -177,7 +172,6 @@ export class DashboardRepository {
         GROUP BY user_id, username, avatar_url
       ) m
       LEFT JOIN ${pgUserProfilesTable} p ON p.user_id = m.user_id
-      LEFT JOIN ${pgUserReputationsTable} r ON r.user_id = m.user_id
       ${whereClause}
       ORDER BY m.last_message_at DESC NULLS LAST
       LIMIT ${limit + 1}
@@ -190,16 +184,6 @@ export class DashboardRepository {
         username: r.username as string | null,
         avatar_url: r.avatar_url as string | null,
         profile_summary: r.profile_summary as string | null,
-        trust_score: r.trust_score != null ? Number(r.trust_score) : null,
-        clean_message_streak:
-          r.clean_message_streak != null
-            ? Number(r.clean_message_streak)
-            : null,
-        total_infractions:
-          r.total_infractions != null ? Number(r.total_infractions) : null,
-        last_infraction_at: r.last_infraction_at
-          ? Number(r.last_infraction_at)
-          : null,
         total_messages: Number(r.total_messages),
         flagged_count: Number(r.flagged_count),
         clean_count: Number(r.clean_count),
@@ -453,11 +437,7 @@ export class DashboardRepository {
         m.clean_count,
         m.warn_count,
         p.profile_summary,
-        p.last_analyzed_at,
-        r.trust_score,
-        r.clean_message_streak,
-        r.total_infractions,
-        r.last_infraction_at
+        p.last_analyzed_at
       FROM (
         SELECT
           user_id,
@@ -472,7 +452,6 @@ export class DashboardRepository {
         GROUP BY user_id, username, avatar_url
       ) m
       LEFT JOIN ${pgUserProfilesTable} p ON p.user_id = m.user_id
-      LEFT JOIN ${pgUserReputationsTable} r ON r.user_id = m.user_id
     `);
 
     const row = userResult.rows[0] as Record<string, unknown> | undefined;
@@ -500,16 +479,6 @@ export class DashboardRepository {
       last_analyzed_at: row.last_analyzed_at
         ? Number(row.last_analyzed_at)
         : null,
-      trust_score: row.trust_score != null ? Number(row.trust_score) : null,
-      clean_message_streak:
-        row.clean_message_streak != null
-          ? Number(row.clean_message_streak)
-          : null,
-      total_infractions:
-        row.total_infractions != null ? Number(row.total_infractions) : null,
-      last_infraction_at: row.last_infraction_at
-        ? Number(row.last_infraction_at)
-        : null,
       recent_messages: (recent.rows as Record<string, unknown>[]).map((r) => ({
         id: String(r.id),
         content: String(r.content),