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/build_parser_wasm.sh

@@ -0,0 +1,45 @@
+#!/usr/bin/env bash
+# Copyright (c) 2026 The xterm.js authors. All rights reserved.
+# @license MIT
+set -euo pipefail
+ROOT="$(cd "$(dirname "$0")/.." && pwd)"
+cd "$ROOT"
+
+if [[ ! -f src/common/parser/wasm/transition_table.h ]]; then
+  npm run build
+  node bin/gen_parser_transition_table.mjs
+fi
+
+WASM_DIR=src/common/parser/wasm
+OUT="$WASM_DIR/parser.wasm"
+
+clang --target=wasm32-unknown-unknown -O2 -nostdlib -fuse-ld=lld \
+  -Wl,--no-entry \
+  -Wl,--export-memory \
+  -Wl,--export=reset \
+  -Wl,--export=scan \
+  -Wl,--export=probe_action \
+  -Wl,--export=set_state \
+  -Wl,--export=sync_params_from \
+  -Wl,--export=export_params_to \
+  -Wl,--export=get_params_len \
+  -Wl,--export=get_subparams_len \
+  -Wl,--export=get_subparams_ptr \
+  -Wl,--export=get_subparams_idx_ptr \
+  -Wl,--export=get_input_ptr \
+  -Wl,--export=get_kinds_ptr \
+  -Wl,--export=get_starts_ptr \
+  -Wl,--export=get_lengths_ptr \
+  -Wl,--export=get_aux_ptr \
+  -Wl,--export=get_param_starts_ptr \
+  -Wl,--export=get_param_counts_ptr \
+  -Wl,--export=get_params_ptr \
+  -Wl,--export=get_state_ptr \
+  -Wl,--export=get_header_ptr \
+  -Wl,--initial-memory=67108864 \
+  -Wl,--max-memory=67108864 \
+  "$WASM_DIR/parser.c" -o "$OUT"
+
+node bin/embed_parser_wasm.mjs
+
+echo "Built $OUT"