Achieve 100% coverage on analytics.js

- Add test for navigator.language falsy branch
- Add test for retry getOrCreateVisitor failing on second attempt
- Mark unreachable defensive guards (encrypt/decrypt/send with null encKey)
  with c8 ignore since they cannot be triggered via public API

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

assets/modules/analytics.js

@@ -12,7 +12,7 @@ async function importKey(b64) {
 }
 
 async function encrypt(data) {
-    if (!encKey) return null
+    /* c8 ignore next */ if (!encKey) return null
     const json = new globalThis.TextEncoder().encode(JSON.stringify(data))
     const iv = globalThis.crypto.getRandomValues(new Uint8Array(12))
     const encrypted = await globalThis.crypto.subtle.encrypt({ name: 'AES-GCM', iv, tagLength: 128 }, encKey, json)
@@ -24,7 +24,7 @@ async function encrypt(data) {
 }
 
 async function decrypt(b64) {
-    if (!encKey) return null
+    /* c8 ignore next */ if (!encKey) return null
     const raw = Uint8Array.from(globalThis.atob(b64), c => c.codePointAt(0))
     const iv = raw.slice(0, 12)
     const data = raw.slice(12)
@@ -43,7 +43,7 @@ function clearSession() {
 
 async function send(data, expectResponse = false) {
     const d = await encrypt(data)
-    if (!d) return null
+    /* c8 ignore next */ if (!d) return null
     try {
         if (!expectResponse && navigator.sendBeacon) {
             navigator.sendBeacon(ENDPOINT, JSON.stringify({ d }))