License sync

[shazzad]

Summary

License sync button

• Add a "Sync" button next to the license key input on the admin page, allowing manual refresh of license data without re-saving the key.
• Extract handle_sync() and handle_save() private methods from load_page() for cleaner separation of the two POST actions.

Extract Client class

• Create src/Client.php with typed public methods: ping(), check_license($license), updates(), details() — replacing the generic Integration::api_request($method, $license) dispatcher.
• Private request() method contains shared HTTP/response logic (URL building, common query args, JSON parsing, error handling).

Store subsystem instances on Integration

• Add public properties $client, $updater, $tracker, $admin to Integration.
• Constructor now stores all subsystem instances instead of discarding them, so classes can reach each other through $this->integration->client, $this->integration->updater, etc.

Update callers

• Updater.php (3 call sites): api_request('updates') → client->updates(), etc.
• Admin.php (3 call sites): api_request('check_license', $key) → client->check_license($key), etc.
• Tracker.php (4 call sites): api_request('ping') → client->ping(), etc.

Update tests

• Rename IntegrationApiRequestTest → ClientApiRequestTest — all tests now exercise $integration->client->method() directly.
• UpdaterPreSetTransientTest now uses $integration->updater instead of creating redundant new Updater() instances.
• Add details_returns_plugin_details test case.

Update docs

• CLAUDE.md and README.md updated to reflect the new Client class, stored subsystem properties, and corrected file structure.

Test plan

• composer test — 39 tests, 70 assertions, all pass
• Manual: verify license admin page renders correctly with sync button
• Manual: verify update checks still inject data into WordPress transient
• Manual: verify license sync cron and activation/deactivation pings work