perf(gateway): hoist correctedExamples query out of retry closure

buildCorrectedFewShotExamples() (a getRecentCorrectedModerations(5)
DB hit) was called inside the per-sub-batch buildContent closure in
textBatchProcessor.ts — re-queried for every sub-batch (≈10× for a
200-msg burst) AND re-fired on each parse-error retry. mediaBatchProcessor
already hoisted it once. Mirror that: fetch once per runTextOnlyBatch,
reuse the cached string inside the closure.

No behavior change — identical content, fewer identical DB reads.
tsc + 129 tests + biome green.

Co-Authored-By: Claude Opus 5 (Nous Research)

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

@@ -195,6 +195,10 @@ export async function runTextOnlyBatch(
     ? await getChannelCulture(channelId)
     : null;
   const channelCulture = channelCultureObj?.culture_summary;
+  // Corrected false-positive examples are static per batch — fetch ONCE
+  // here instead of inside the per-sub-batch retry closure (which would
+  // re-query the DB on every sub-batch and every parse-error retry).
+  const correctedExamples = await buildCorrectedFewShotExamples();
 
   for (let i = 0; i < subBatches.length; i++) {
     const batch = subBatches[i];
@@ -296,7 +300,6 @@ export async function runTextOnlyBatch(
             preview: state.lastInvalidContent?.slice(0, 800) ?? "<empty>",
           }
         : undefined;
-      const correctedExamples = await buildCorrectedFewShotExamples();
       const systemText = buildSystemPromptModular({
         mode: batchHasImageEvidence ? "mixed" : "text",
         correction,