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>

tests/js/analytics.test.js

@@ -293,6 +293,56 @@ describe('analytics.js', () => {
         expect(beaconMock).not.toHaveBeenCalled()
     })
 
+    it('covers navigator.language being undefined', async () => {
+        const key = await realImportKey(TEST_KEY_B64)
+        const visitorResp = await realEncrypt({ uid: 'vl', h: 'hashl' }, key)
+
+        document.body.dataset.k = TEST_KEY_B64
+        document.body.dataset.e = '/t'
+
+        const origLang = navigator.language
+        Object.defineProperty(navigator, 'language', { value: '', configurable: true })
+
+        fetchMock.mockResolvedValue({
+            ok: true, status: 200, json: async () => ({ d: visitorResp }),
+        })
+
+        const { initAnalytics } = await loadModule()
+        await initAnalytics()
+
+        Object.defineProperty(navigator, 'language', { value: origLang, configurable: true })
+
+        expect(fetchMock).toHaveBeenCalledTimes(1)
+    })
+
+    it('retry getOrCreateVisitor fails on second attempt after 403', async () => {
+        const key = await realImportKey(TEST_KEY_B64)
+        const visitorResp = await realEncrypt({ uid: 'v6', h: 'hash6' }, key)
+
+        document.body.dataset.k = TEST_KEY_B64
+        document.body.dataset.e = '/t'
+
+        navigator.sendBeacon = undefined
+
+        let callCount = 0
+        fetchMock.mockImplementation(async () => {
+            callCount++
+            // 1st: visitor creation succeeds
+            if (callCount === 1) return { ok: true, status: 200, json: async () => ({ d: visitorResp }) }
+            // 2nd: trackPageView gets 403 -> clears session
+            if (callCount === 2) return { ok: false, status: 403 }
+            // 3rd: second getOrCreateVisitor also fails (204 = no body)
+            return { ok: true, status: 204 }
+        })
+
+        const { initAnalytics } = await loadModule()
+        await initAnalytics()
+
+        // After 403, retry creates visitor (call 3) but gets 204 -> null visitor -> early return
+        expect(callCount).toBe(3)
+        expect(sessionStorage.getItem('_u')).toBeNull()
+    })
+
     it('setAuth sends when session and key exist', async () => {
         const key = await realImportKey(TEST_KEY_B64)
         const visitorResp = await realEncrypt({ uid: 'v5', h: 'hash5' }, key)