Web playground example

[emuell]

• allow compiling afseq with emscripten
• add web playground example

Unfortunately the example can't be hosted as github page, because it needs to be served with COOP and COEP headers for WebAssembly Threads. See https://github.com/orgs/community/discussions/13309

[github-actions]

Benchmark for 7d5c37c

Click to view benchmark

Test	Base	PR	%
Cycle/Generate	48.1±0.30µs	48.2±0.87µs	+0.21%
Cycle/Parse	360.8±10.89µs	363.6±5.86µs	+0.78%
Rust Phrase/Clone	433.7±5.67ns	432.1±5.18ns	-0.37%
Rust Phrase/Create	73.4±1.60µs	72.1±1.76µs	-1.77%
Rust Phrase/Run	639.4±4.45µs	625.7±5.49µs	-2.14%
Rust Phrase/Seek	135.1±247.95µs	134.5±247.84µs	-0.44%
Scripted Phrase/Clone	652.8±7.78ns	654.0±10.10ns	+0.18%
Scripted Phrase/Create	961.4±10.55µs	954.8±12.84µs	-0.69%
Scripted Phrase/Run	1652.0±21.45µs	1656.5±55.05µs	+0.27%
Scripted Phrase/Seek	214.1±433.35µs	212.9±429.62µs	-0.56%

[github-actions]

Benchmark for 4912f45

Click to view benchmark

Test	Base	PR	%
Cycle/Generate	48.9±0.52µs	49.1±0.63µs	+0.41%
Cycle/Parse	372.2±11.81µs	363.3±12.59µs	-2.39%
Rust Phrase/Clone	434.1±5.19ns	452.4±5.17ns	+4.22%
Rust Phrase/Create	71.9±1.46µs	72.6±1.85µs	+0.97%
Rust Phrase/Run	634.4±4.42µs	647.2±5.26µs	+2.02%
Rust Phrase/Seek	138.9±258.19µs	139.1±259.27µs	+0.14%
Scripted Phrase/Clone	657.7±24.86ns	663.1±15.31ns	+0.82%
Scripted Phrase/Create	964.4±19.14µs	941.1±9.53µs	-2.42%
Scripted Phrase/Run	1659.3±15.59µs	1716.2±18.11µs	+3.43%
Scripted Phrase/Seek	235.4±477.32µs	218.5±442.63µs	-7.18%