feat(parser): WASM VT500 scanner with ScanResult SOA dispatch

- Add C WASM scanner emitting structure-of-arrays ops (kinds, starts, lengths, aux, params)
- Integrate scan+dispatch in EscapeSequenceParser with async handler resume
- Fix CSI fast-path final byte index, ERROR state reporting, and precedingJoinState for REP
- Add build pipeline (build_parser_wasm.sh, transition table generator, wasm embed)

Co-authored-by: Daniel Imms <Tyriar@users.noreply.github.com>

bin/embed_parser_wasm.mjs

@@ -0,0 +1,23 @@
+/**
+ * Copyright (c) 2026 The xterm.js authors. All rights reserved.
+ * @license MIT
+ */
+
+import { readFileSync, writeFileSync } from 'fs';
+import { join, dirname } from 'path';
+import { fileURLToPath } from 'url';
+
+const __dirname = dirname(fileURLToPath(import.meta.url));
+const root = join(__dirname, '..');
+const wasm = readFileSync(join(root, 'src/common/parser/wasm/parser.wasm'));
+const b64 = wasm.toString('base64');
+
+const out = `/**
+ * Copyright (c) 2026 The xterm.js authors. All rights reserved.
+ * @license MIT
+ */
+/** Base64-encoded parser.wasm (generated by bin/build_parser_wasm.sh) */
+export const PARSER_WASM_BASE64 = '${b64}';\n`;
+
+writeFileSync(join(root, 'src/common/parser/wasm/parser.wasm.embed.ts'), out);
+console.info(`Embedded parser.wasm (${wasm.length} bytes)`);