Warning screen, smarter license re-validation, version reporting

Warning screen
- New reusable WarningPage (word-wrapped message, ENTER acknowledges and
  continues to the screen you were about to enter).
- First use: pressing Play while the selected audio is still downloading.
  Dynamic Audio requires every file; a fixed track requires its own file.

License re-validation
- No longer re-verifies on every Home render. Checks now run only when the
  email/license key is entered or changed, on the manual option, at startup
  when already due, and hourly while valid.
- Invalid + unchanged credentials are never re-checked (persisted pair).
- Valid re-checks at most once per hour, anchored on a DB timestamp so an
  overdue check runs immediately after a power cycle.
- New system_kv keys track the checked pair, outcome, and last-check time.
- Added a System Settings row "Manually Validate License Key OK|Invalid"
  (OK green, Invalid red, label white) that runs a check immediately.

Portal / local integration
- License validation request now sends the app version as `appVersion`.
- The entered license key is mirrored to ~/.local/radiantwave/license.txt.

Misc
- "Please connect to WiFi" only shows when no WiFi is joined AND the internet
  is unreachable (fixes the NetworkManager-missing and Ethernet cases).
- Added unit tests for the audio-download warning, license scheduling policy,
  license request shape, and the new settings-menu entry.

tests/test_license_status.cpp

@@ -97,6 +97,46 @@ TEST(LicenseStatusTest, StatusForResultWithGraceExpired) {
     EXPECT_EQ(statusForResultWithGrace(Result::NetworkError, tmp.db), Status::Invalid);
 }
 
+// ─── Scheduling policy (pure) ───────────────────────────────────────────
+
+TEST(LicenseStatusPolicyTest, ForcedAlwaysRuns) {
+    EXPECT_TRUE(shouldValidate(true, false, false, Status::Invalid, 1000, 999));
+    EXPECT_TRUE(shouldValidate(true, false, false, Status::Unknown, 1000, 0));
+}
+
+TEST(LicenseStatusPolicyTest, CredentialChangeRuns) {
+    EXPECT_TRUE(shouldValidate(false, true, false, Status::Invalid, 1000, 999));
+}
+
+TEST(LicenseStatusPolicyTest, OverdueRecheckRuns) {
+    EXPECT_TRUE(shouldValidate(false, false, true, Status::Invalid, 1000, 999));
+}
+
+TEST(LicenseStatusPolicyTest, InvalidUnchangedDoesNotRun) {
+    // An invalid license with unchanged credentials is never re-checked, no
+    // matter how old the last attempt is.
+    EXPECT_FALSE(shouldValidate(false, false, false, Status::Invalid, 1000, 999));
+    EXPECT_FALSE(shouldValidate(false, false, false, Status::Invalid,
+                                1000, 1000 - 10 * RECHECK_INTERVAL_SECONDS));
+    EXPECT_FALSE(shouldValidate(false, false, false, Status::Unknown, 1000, 0));
+}
+
+TEST(LicenseStatusPolicyTest, ValidRechecksAfterInterval) {
+    const long long now = 1000000;
+    EXPECT_FALSE(shouldValidate(false, false, false, Status::Valid, now, now - 10));
+    EXPECT_FALSE(shouldValidate(false, false, false, Status::Valid, now,
+                                now - (RECHECK_INTERVAL_SECONDS - 1)));
+    EXPECT_TRUE(shouldValidate(false, false, false, Status::Valid, now,
+                               now - RECHECK_INTERVAL_SECONDS));
+    // Off for several hours: still immediately due, not another full hour away.
+    EXPECT_TRUE(shouldValidate(false, false, false, Status::Valid, now,
+                               now - 5 * RECHECK_INTERVAL_SECONDS));
+}
+
+TEST(LicenseStatusPolicyTest, ValidWithMissingStampRechecks) {
+    EXPECT_TRUE(shouldValidate(false, false, false, Status::Valid, 1000, 0));
+}
+
 // ─── Worker lifecycle (no network) ──────────────────────────────────────
 
 TEST(LicenseStatusTest, UnknownBeforeStart) {
@@ -130,6 +170,50 @@ TEST(LicenseStatusTest, InvalidWhenDatabaseClosed) {
     tracker.shutdown();
 }
 
+TEST(LicenseStatusTest, LoadsPersistedValidWithinGraceWithoutChecking) {
+    TempDb tmp;
+    tmp.db.setKV(KV_LICENSE_KEY, "k");
+    tmp.db.setKV(KV_EMAIL_ADDRESS, "e");
+    tmp.db.setKV(KV_LICENSE_CHECKED_KEY, "k");
+    tmp.db.setKV(KV_LICENSE_CHECKED_EMAIL, "e");
+    tmp.db.setKV(KV_LICENSE_CHECK_STATUS, "valid");
+    tmp.db.setKV(KV_LICENSE_LAST_VERIFIED, std::to_string(epochSeconds()));
+    tmp.db.setKV(KV_LICENSE_LAST_CHECK, std::to_string(epochSeconds()));
+
+    LicenseStatusTracker tracker;
+    tracker.start(tmp.db);
+    // Seeded valid + recently checked + unchanged credentials: the worker must
+    // stay idle (no network), and the status is valid immediately.
+    EXPECT_EQ(tracker.status(), Status::Valid);
+    tracker.shutdown();
+}
+
+TEST(LicenseStatusTest, RecordResultUpdatesStatusAndPersistsCheckedPair) {
+    TempDb tmp;
+    const std::string key = "AAAA-BBBB-CCCC-DDDD";
+    const std::string email = "user@example.com";
+    tmp.db.setKV(KV_LICENSE_KEY, key);
+    tmp.db.setKV(KV_EMAIL_ADDRESS, email);
+    // Seed the checked pair as already-invalid so the worker does not start a
+    // network check; this exercises recordResult() in isolation.
+    tmp.db.setKV(KV_LICENSE_CHECKED_KEY, key);
+    tmp.db.setKV(KV_LICENSE_CHECKED_EMAIL, email);
+    tmp.db.setKV(KV_LICENSE_CHECK_STATUS, "invalid");
+
+    LicenseStatusTracker tracker;
+    tracker.start(tmp.db);
+    EXPECT_EQ(tracker.status(), Status::Invalid);
+
+    tracker.recordResult(Result::Ok);
+    EXPECT_EQ(tracker.status(), Status::Valid);
+    EXPECT_TRUE(tracker.isValid());
+    EXPECT_EQ(tmp.db.getKV(KV_LICENSE_CHECKED_KEY), key);
+    EXPECT_EQ(tmp.db.getKV(KV_LICENSE_CHECKED_EMAIL), email);
+    EXPECT_EQ(tmp.db.getKV(KV_LICENSE_CHECK_STATUS), "valid");
+    EXPECT_FALSE(tmp.db.getKV(KV_LICENSE_LAST_CHECK).empty());
+    tracker.shutdown();
+}
+
 // ─── Live: confirmed-valid license (requires env credentials) ───────────
 
 TEST(LicenseStatusLiveTest, ValidWhenLicensePairAccepted) {