Add emoji and Unicode symbol stripping to TTS sanitizer

Adds safety net sanitization to strip emojis, Unicode arrows, math
operators, and other unpronouneable symbols before TTS playback.
This ensures clean voice output even when agent responses contain
special characters.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Author: sanchitmonga22

extensions/voice-assistant/src/tts-sanitize.ts

@@ -82,6 +82,29 @@ export function sanitizeForTTS(text: string): string {
   // Curly braces, pipes, backslashes
   result = result.replace(/[{}|\\]/g, "");
 
+  // --- Remove emojis and Unicode symbols (TTS safety net) ---
+
+  // Emojis - remove all Unicode emoji characters
+  result = result.replace(/[\u{1F300}-\u{1F9FF}]/gu, ""); // Misc symbols, emoticons
+  result = result.replace(/[\u{2600}-\u{26FF}]/gu, ""); // Misc symbols
+  result = result.replace(/[\u{2700}-\u{27BF}]/gu, ""); // Dingbats
+  result = result.replace(/[\u{FE00}-\u{FE0F}]/gu, ""); // Variation selectors
+  result = result.replace(/[\u{1F000}-\u{1F02F}]/gu, ""); // Mahjong, dominos
+  result = result.replace(/[\u{1F0A0}-\u{1F0FF}]/gu, ""); // Playing cards
+
+  // Unicode arrows and symbols that TTS can't pronounce
+  result = result.replace(/[\u{2190}-\u{21FF}]/gu, ""); // Arrows
+  result = result.replace(/[\u{2200}-\u{22FF}]/gu, ""); // Math operators
+  result = result.replace(/[\u{2300}-\u{23FF}]/gu, ""); // Misc technical
+  result = result.replace(/[\u{25A0}-\u{25FF}]/gu, ""); // Geometric shapes
+  result = result.replace(/[\u{2500}-\u{257F}]/gu, ""); // Box drawing
+
+  // Common special characters that slip through
+  result = result.replace(/[•◦‣►▶◀▷▸▹▼▽△▲★☆♠♣♥♦©®™±×÷]/g, "");
+
+  // Degree symbol - keep the number, remove the symbol
+  result = result.replace(/°/g, " degrees ");
+
   // --- Normalize whitespace ---
 
   // Collapse 3+ newlines into double newline (natural pause)