fix(discord-gateway): resolve type errors in error logging - cast unknown error types to Error | string for logModerationError calls

- aiAnalyzer.ts: cast error to Error | string in individual fallback phase
- llmModerationClient.ts: cast parseError to Error | string in parse response phase

Fixes GitHub Actions build failure (exit code 2)

services/discord-gateway/src/modules/ai-moderation/aiAnalyzer.ts

@@ -450,7 +450,7 @@ async function processIndividualFallback(
     lastError = error instanceof Error ? error.message : String(error);
 
     // Log error with responseLogger
-    logModerationError([messageId], config.AI_LLM_MODEL, error, {
+    logModerationError([messageId], config.AI_LLM_MODEL, error as Error | string, {
       phase: "individual_fallback",
       conversationKey,
       exhaustedOnIncomplete,

services/discord-gateway/src/modules/ai-moderation/llmModerationClient.ts

@@ -796,7 +796,7 @@ async function callModerationLLM(
     );
 
     // Log error with responseLogger
-    logModerationError(targetIds, config.AI_LLM_MODEL, parseError, {
+    logModerationError(targetIds, config.AI_LLM_MODEL, parseError as Error | string, {
       phase: "parse_response",
       label,
       contentLength: state.lastInvalidContent.length,