feat(monospace): add MonospaceFontConfig path resolver

Resolves dev vs packaged (asar.unpacked) TTF paths. Logs warn, returns null
when bundled font is missing.

src/main/MonospaceFontConfig.js

@@ -0,0 +1,44 @@
+'use strict';
+
+const fs = require('fs');
+const path = require('path');
+const { app } = require('electron');
+const { getActiveMonoFont, isLigaturesEnabled, FAMILY_BY_KEY } = require('./settings/monospaceSettings');
+
+const WEIGHT_BY_KEY = { 300: 'Light', 400: 'Regular', 500: 'Medium', 600: 'SemiBold', 700: 'Bold' };
+
+function getAppRoot() {
+  if (process.resourcesPath && fs.existsSync(path.join(process.resourcesPath, 'app.asar.unpacked'))) {
+    return process.resourcesPath;
+  }
+  return path.resolve(__dirname, '..', '..');
+}
+
+function getCandidatePaths(family, weight) {
+  const familyDir = family === 'Fira Code' ? 'FiraCode' : 'JetBrainsMono';
+  const weightName = WEIGHT_BY_KEY[weight] || 'Regular';
+  const filename = `${familyDir}-${weightName}.ttf`;
+
+  const candidates = [];
+  candidates.push(path.resolve(getAppRoot(), 'assets', 'fonts', filename));
+  const packagedRoot = process.resourcesPath || getAppRoot();
+  candidates.push(path.join(packagedRoot, 'app.asar.unpacked', 'assets', 'fonts', filename));
+  return candidates;
+}
+
+function getMonoFontTtfPath(familyKey, weight = 400) {
+  const family = FAMILY_BY_KEY[familyKey] || 'JetBrains Mono';
+  const candidates = getCandidatePaths(family, weight);
+  for (const p of candidates) {
+    if (fs.existsSync(p)) return p;
+  }
+  const filename = path.basename(candidates[candidates.length - 1]);
+  console.warn(`[MonospaceFontConfig] bundled font missing: ${filename}; falling back to system monospace`);
+  return null;
+}
+
+function ligaturesEnabled(settings) { return isLigaturesEnabled(settings); }
+
+function getActiveFamily(settings) { return getActiveMonoFont(settings); }
+
+module.exports = { getMonoFontTtfPath, ligaturesEnabled, getActiveFamily };