feat(config): add getGuildConfig() for database-backed guild settings

Add function to fetch guild-specific config from database with:
- 60-second cache TTL
- Fallback to file-based config for migration period
- Cache invalidation helper

shared/lib/config.ts

@@ -5,6 +5,85 @@ import { z } from 'zod';
 
 const configPath = join(import.meta.dir, '..', 'config', 'config.json');
 
+export interface GuildConfig {
+    studentRole?: string;
+    visitorRole?: string;
+    colorRoles: string[];
+    welcomeChannelId?: string;
+    welcomeMessage?: string;
+    feedbackChannelId?: string;
+    terminal?: {
+        channelId: string;
+        messageId: string;
+    };
+    moderation: {
+        cases: {
+            dmOnWarn: boolean;
+            logChannelId?: string;
+            autoTimeoutThreshold?: number;
+        };
+    };
+}
+
+const guildConfigCache = new Map<string, { config: GuildConfig; timestamp: number }>();
+const CACHE_TTL_MS = 60000;
+
+export async function getGuildConfig(guildId: string): Promise<GuildConfig> {
+    const cached = guildConfigCache.get(guildId);
+    if (cached && Date.now() - cached.timestamp < CACHE_TTL_MS) {
+        return cached.config;
+    }
+
+    try {
+        const { guildSettingsService } = await import('@shared/modules/guild-settings/guild-settings.service');
+        const dbSettings = await guildSettingsService.getSettings(guildId);
+
+        if (dbSettings) {
+            const config: GuildConfig = {
+                studentRole: dbSettings.studentRoleId,
+                visitorRole: dbSettings.visitorRoleId,
+                colorRoles: dbSettings.colorRoleIds ?? [],
+                welcomeChannelId: dbSettings.welcomeChannelId,
+                welcomeMessage: dbSettings.welcomeMessage,
+                feedbackChannelId: dbSettings.feedbackChannelId,
+                terminal: dbSettings.terminalChannelId ? {
+                    channelId: dbSettings.terminalChannelId,
+                    messageId: dbSettings.terminalMessageId ?? "",
+                } : undefined,
+                moderation: {
+                    cases: {
+                        dmOnWarn: dbSettings.moderationDmOnWarn ?? true,
+                        logChannelId: dbSettings.moderationLogChannelId,
+                        autoTimeoutThreshold: dbSettings.moderationAutoTimeoutThreshold,
+                    },
+                },
+            };
+
+            guildConfigCache.set(guildId, { config, timestamp: Date.now() });
+            return config;
+        }
+    } catch (error) {
+        console.error("Failed to load guild config from database:", error);
+    }
+
+    const fileConfig: GuildConfig = {
+        studentRole: config.studentRole,
+        visitorRole: config.visitorRole,
+        colorRoles: config.colorRoles,
+        welcomeChannelId: config.welcomeChannelId,
+        welcomeMessage: config.welcomeMessage,
+        feedbackChannelId: config.feedbackChannelId,
+        terminal: config.terminal,
+        moderation: config.moderation,
+    };
+
+    return fileConfig;
+}
+
+export function invalidateGuildConfigCache(guildId: string) {
+    guildConfigCache.delete(guildId);
+}
+
 export interface GameConfigType {
     leveling: {
         base: number;