Refresh player with native block editor preview and local assets

Preserve shortcode rendering, normalize options, bundle the player locally,
and add reproducible packaging and WordPress integration tests.

SOURCE.md

@@ -0,0 +1,35 @@
+# Source and reproducible build
+
+This distribution contains the plugin's PHP and JavaScript source, block metadata,
+build configuration, scripts, and npm lockfile. The development repository is
+https://github.com/LamGC/wp-asciiplayer .
+
+Use Node.js 24 (24.15 or later), npm, and the standard `zip` command:
+
+    npm ci
+    npm run build
+    npm run package
+
+The installable output is `dist/wp-asciiplayer.zip`. Generated assets are never
+loaded from a CDN. `scripts/vendor.mjs` copies the pinned official npm
+`[email protected]` distribution, verified by package-lock integrity, into
+`build/player.js` and `build/player.css`. WordPress-provided JavaScript packages
+are externalized by @wordpress/scripts, not bundled with a second React.
+
+The upstream player's corresponding source and build instructions are at
+https://github.com/asciinema/asciinema-player/tree/v3.17.0 . Its JavaScript bundle
+includes the upstream terminal WebAssembly implementation. Third-party notices
+and applicable license texts are included alongside this file.
+
+Development tests require the full repository (tests are not in the install ZIP):
+
+    npm test
+    npm run test:php
+    npm run wp-env -- start
+    npm run test:e2e
+
+PHP tests require a PHP runtime. WordPress integration tests require Docker and
+Chromium; the repository CI records the exact WordPress version under test and
+installs the release ZIP into the test site before checking it. Refer to the
+workflow for setup details. Running a unit test is not a substitute for the
+WordPress browser integration suite.