feat(wasm): build the full workspace (minus python-native) for browser wasm32

[Roger-luo]

Summary

Follow-up to #143 (now merged): #143 made the compile gates generic; this PR
closes the dependency / feature-graph blockers so the whole workspace
except ppvm-python-native cross-compiles to wasm32-unknown-unknown
(browser / wasm-bindgen) — cargo build --target wasm32-unknown-unknown with
no extra flags. Native builds keep gxhash/dashmap/ahash/rayon and are
byte-for-byte unchanged.

Mechanism (automatic)

Cargo prunes a dependency under [target.'cfg(not(target_arch = "wasm32"))'.dependencies]
on wasm, but the feature named after it stays on, so #[cfg(feature = "X")]
code would still try to compile against the absent crate. The fix is two
coordinated moves per native-only dep: target-gate the dep and gate its code
sites with the same not(target_arch = "wasm32"). The features then go inert on
wasm, so no default-features = false propagation through the inter-crate deps
is needed.

Changes

• ppvm-traits — target-gate ahash/dashmap/gxhash/rayon; gate the
  dashmap map module, the ahash ACMap impls, and the gxhash HashFinalize impl.
• ppvm-pauli-word — target-gate gxhash.
• ppvm-pauli-sum — target-gate dashmap/gxhash; gate the
  config::dashmap module and config::indexmap's ByteGxHash/ByteGxHashF64
  (also fixes a latent indexmap-without-gxhash coupling).
• ppvm-tableau-sum — target-gate gxhash/rayon; word_fingerprint
  falls back from GxHasher to fxhash::FxHasher on wasm (a transient in-memory
  dedup hash, resolved by structurally_equal, never persisted or compared
  across platforms).
• ppvm-tableau / ppvm-stim — target-gate rayon (no OS threads on wasm).
• rand entropy — rand::make_rng() has no default source on
  wasm32-unknown-unknown, so select getrandom's wasm_js (Web Crypto) backend
  via a --cfg getrandom_backend="wasm_js" rustflag in .cargo/config.toml plus
  the wasm_js feature in ppvm-tableau's wasm-only dep table; feature
  unification covers tableau-sum / stim / top-level ppvm.
• CI — new wasm32 build (browser) job cross-compiles the workspace on every PR.
• docs — WebAssembly subsection in develop.astro.

Verification

• Native cargo test --workspace (excl. python-native's macOS test-link issue):
  744 passed, 0 failed.
• Native --all-targets and the ppvm-python-native cdylib build unchanged.
• Full workspace builds for wasm32-unknown-unknown — incl. ppvm-tableau,
  ppvm-tableau-sum, ppvm-stim, and the top-level ppvm crate.
• On wasm the dependency tree drops ahash/gxhash/getrandom 0.3 entirely,
  leaving only getrandom 0.4 (wasm_js) for rand.

🤖 Generated with Claude Code

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2026-06-23 06:19 UTC

[Roger-luo]

No performance impact on native builds. Every change in this PR is wasm-only — a cfg(not(target_arch = "wasm32")) dependency-table move or code gate, or the new FingerprintHasher alias that resolves to the existing GxHasher on native — so the native dependency + feature tree is byte-for-byte identical to main and the compiled native code is unchanged. A ppvm-tableau-sum storage_compare comparison against a main baseline confirmed this empirically: the deltas were pure measurement noise (the vec path, which this PR cannot touch, swung +8.9% then −3.2% across two runs of the identical binary).

[Roger-luo]

I think WASM is fully supported now.

cc: @rafaelha

[rafaelha]

Confirming that WASM compilation works for me now