Refactor: Fix string/binary handling and improve type consistency

[Copilot]

Applies code review fixes for unnecessary complexity in string handling, incorrect binary data conversion methods, and inconsistent null/undefined usage.

Changes

• server/index.js: Replace String.raw template with regular string literal for newline replacement
• server/index.js: Add length validation (6-32 digits) to normalizePhone() to validate normalized output
• services/firebaseClient.ts: Remove undefined from type unions, use null consistently for uninitialized state
• services/geminiService.ts: Replace String.fromCodePoint() with String.fromCharCode() for byte-to-string conversion
• utils/metadata.ts: Replace codePointAt() with charCodeAt() for base64 binary decoding
• vite.config.ts: Extract hardcoded base path to VITE_PROD_BASE_PATH env var

Binary data fix

fromCodePoint/codePointAt handle Unicode code points which can exceed byte range. For binary data (0-255), fromCharCode/charCodeAt is correct:

// Before (incorrect for binary)
bytes[i] = binary.codePointAt(i) ?? 0;

// After
bytes[i] = binary.charCodeAt(i);

Original prompt

Please apply the following diffs and create a pull request.
Once the PR is ready, give it a title based on the messages of the fixes being applied.

[{"message":"Using String.raw template literal for a simple string replacement is unnecessarily complex. Use a regular string literal instead: rawPrivateKey.replaceAll('\\\\n', '\\n').","fixFiles":[{"filePath":"server/index.js","diff":"diff --git a/server/index.js b/server/index.js\n--- a/server/index.js\n+++ b/server/index.js\n@@ -124,7 +124,7 @@\n   const projectId = process.env.FIREBASE_PROJECT_ID;\n   const clientEmail = process.env.FIREBASE_CLIENT_EMAIL;\n   const rawPrivateKey = process.env.FIREBASE_PRIVATE_KEY;\n-  const privateKey = rawPrivateKey ? rawPrivateKey.replaceAll(String.raw`\\n`, '\\n') : undefined;\n+  const privateKey = rawPrivateKey ? rawPrivateKey.replaceAll('\\\\n', '\\n') : undefined;\n \n   if (projectId && clientEmail && privateKey) {\n     if (!admin.apps.length) {\n"}]},{"message":"The phone normalization only removes non-digits but doesn't validate the result. Consider adding validation to ensure the normalized phone number has a reasonable length and format before processing.","fixFiles":[{"filePath":"server/index.js","diff":"diff --git a/server/index.js b/server/index.js\n--- a/server/index.js\n+++ b/server/index.js\n@@ -179,7 +179,15 @@\n });\n \n const normalizeEmail = (email) => email.trim().toLowerCase();\n-const normalizePhone = (phone) => phone.replaceAll(/\\D/g, '');\n+const normalizePhone = (phone) => {\n+  const digits = phone.replaceAll(/\\D/g, '');\n+  const minLen = 6;\n+  const maxLen = 32;\n+  if (digits.length < minLen || digits.length > maxLen) {\n+    throw new Error('Normalized phone number has invalid length.');\n+  }\n+  return digits;\n+};\n \n const normalizeAddress = (address) => {\n   if (typeof address !== 'string' || !address.startsWith('0x')) {\n"}]},{"message":"Using both null and undefined in the type union creates ambiguity. Choose either null or undefined consistently for uninitialized state to improve code clarity and reduce confusion.","fixFiles":[{"filePath":"services/firebaseClient.ts","diff":"diff --git a/services/firebaseClient.ts b/services/firebaseClient.ts\n--- a/services/firebaseClient.ts\n+++ b/services/firebaseClient.ts\n@@ -22,8 +22,8 @@\n   type UserCredential,\n } from 'firebase/auth';\n \n-let firebaseApp: FirebaseApp | null | undefined;\n-let firebaseAuth: Auth | null | undefined;\n+let firebaseApp: FirebaseApp | null;\n+let firebaseAuth: Auth | null;\n \n const loadFirebaseConfig = () => {\n   const apiKey = import.meta.env.VITE_FIREBASE_API_KEY;\n@@ -50,7 +50,7 @@\n };\n \n const ensureFirebase = (): { app: FirebaseApp; auth: Auth } | null => {\n-  if (firebaseAuth !== undefined && firebaseApp !== undefined) {\n+  if (firebaseAuth !== null && firebaseApp !== null) {\n     if (firebaseApp && firebaseAuth) {\n       return { app: firebaseApp, auth: firebaseAuth };\n     }\n"}]},{"message":"Using both null and undefined in the type union creates ambiguity. Choose either null or undefined consistently for uninitialized state to improve code clarity and reduce confusion.","fixFiles":[{"filePath":"services/firebaseClient.ts","diff":"diff --git a/services/firebaseClient.ts b/services/firebaseClient.ts\n--- a/services/firebaseClient.ts\n+++ b/services/firebaseClient.ts\n@@ -22,8 +22,8 @@\n   type UserCredential,\n } from 'firebase/auth';\n \n-let firebaseApp: FirebaseApp | null | undefined;\n-let firebaseAuth: Auth | null | undefined;\n+let firebaseApp: FirebaseApp | null;\n+let firebaseAuth: Auth | null;\n \n const loadFirebaseConfig = () => {\n   const apiKey = import.meta.env.VITE_FIREBASE_API_KEY;\n@@ -50,7 +50,7 @@\n };\n \n const ensureFirebase = (): { app: FirebaseApp; auth: Auth } | null => {\n-  if (firebaseAuth !== undefined && firebaseApp !== undefined) {\n+  if (firebaseAuth !== null && firebaseApp !== null) {\n     if (firebaseApp && firebaseAuth) {\n       return { app: firebaseApp, auth: firebaseAuth };\n     }\n"}]},{"message":"Using String.fromCodePoint() for binary data conversion is incorrect. For converting bytes to a binary string for btoa(), use String.fromCharCode() instead, as fromCodePoint() is designed for Unicode code points, not raw byte values.","fixFiles":[{"filePath":"services/geminiService.ts","diff":"diff --git a/services/geminiService.ts b/services/geminiService.ts\n--- a/services/geminiService.ts\n+++ b/services/geminiService.ts\n@@ -263,7 +263,7 @@\n         const bytes = new Uint8Array(result);\n         let binary = '';\n         for (let i = 0; i < bytes.byteLength; i++) {\n-          binary += String.fromCodePoint(bytes[i]);\n+          binary += String.fromCharCode(bytes[i]);\n         }\n         resolve(btoa(binary));\n       } else {\n"}]},{"message":"Using codePointAt() for binary data conversion is incorrect. Binary strings from atob() contain byte values 0-255, but codePointAt() returns Unicode code points which can be much lar...

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