feat(moderation): Indonesian slang normalizer and false-positive prevention

- Add indonesian-badwords dependency for local lexical signal
- Add Indonesian slang lexicon with woy/woi/hadeh as safe casual terms
- Normalize Discord custom emoji <:name:id> to [emoji:name] in prompts
- Wire normalization evidence into both conversationContext and llmModerationClient prompts
- Harden system prompt: woy/woi are casual greetings, not SARA/hate
- Add tests for emoji normalization, slang mapping, badword detection

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

src/moderation/indonesianTextNormalizer.ts

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+import badwordsModule from "indonesian-badwords";
+import { INDONESIAN_SLANG_LEXICON } from "./resources/indonesianSlangLexicon.js";
+
+const CUSTOM_EMOJI_PATTERN = /<a?:([a-zA-Z0-9_]+):(\d+)>/g;
+const WORD_PATTERN = /[\p{L}\p{N}_]+/gu;
+
+interface BadwordAnalyzeResult {
+  badwords?: string[];
+  count?: number;
+}
+
+interface BadwordsModule {
+  analyze?: (text: string) => BadwordAnalyzeResult;
+  flag?: (text: string) => boolean;
+}
+
+const badwords = badwordsModule as BadwordsModule;
+
+export interface ModerationTextEvidence {
+  raw: string;
+  normalized: string;
+  notes: string[];
+  badwords: string[];
+  hasBadwords: boolean;
+}
+
+export function normalizeDiscordCustomEmoji(text: string): {
+  text: string;
+  emojiNames: string[];
+} {
+  const emojiNames: string[] = [];
+  const normalized = text.replace(CUSTOM_EMOJI_PATTERN, (_match, name: string) => {
+    emojiNames.push(name);
+    return `[emoji:${name}]`;
+  });
+
+  return { text: normalized, emojiNames };
+}
+
+export function normalizeIndonesianSlang(text: string): {
+  text: string;
+  notes: string[];
+} {
+  const notes: string[] = [];
+  const normalized = text.replace(WORD_PATTERN, (word) => {
+    const entry = INDONESIAN_SLANG_LEXICON[word.toLowerCase()];
+    if (!entry) return word;
+
+    notes.push(`${word}=${entry.normalized} (${entry.note})`);
+    return entry.normalized;
+  });
+
+  return { text: normalized, notes: Array.from(new Set(notes)) };
+}
+
+export function detectIndonesianBadwords(text: string): string[] {
+  try {
+    const result = badwords.analyze?.(text);
+    if (Array.isArray(result?.badwords)) {
+      return Array.from(new Set(result.badwords.map((word) => word.toLowerCase())));
+    }
+  } catch {
+    // Keep moderation pipeline resilient if dependency changes shape.
+  }
+  return [];
+}
+
+export function buildModerationTextEvidence(text: string): ModerationTextEvidence {
+  const emojiNormalized = normalizeDiscordCustomEmoji(text);
+  const slangNormalized = normalizeIndonesianSlang(emojiNormalized.text);
+  const badwordHits = detectIndonesianBadwords(slangNormalized.text);
+  const notes = [...slangNormalized.notes];
+
+  for (const emojiName of emojiNormalized.emojiNames) {
+    notes.push(
+      `emoji:${emojiName}=Discord custom emoji/expression; not text offense by default`,
+    );
+  }
+
+  if (badwordHits.length > 0) {
+    notes.push(`local lexical check: Indonesian badword detected: ${badwordHits.join(", ")}`);
+  } else {
+    notes.push("local lexical check: no Indonesian badword detected");
+  }
+
+  return {
+    raw: text,
+    normalized: slangNormalized.text,
+    notes: Array.from(new Set(notes)),
+    badwords: badwordHits,
+    hasBadwords: badwordHits.length > 0,
+  };
+}
+
+export function formatModerationTextEvidenceForPrompt(text: string): string {
+  const evidence = buildModerationTextEvidence(text);
+  if (evidence.normalized === evidence.raw && evidence.notes.length === 0) {
+    return "";
+  }
+
+  return [
+    `[normalized_text: ${evidence.normalized}]`,
+    evidence.notes.length > 0 ? `[normalization_notes: ${evidence.notes.join("; ")}]` : null,
+  ]
+    .filter(Boolean)
+    .join(" ");
+}