ci: Fix Release Docs wasm build (#2603)

## Description

The Release Docs workflow has been failing since June. This PR fixes the
two build errors in the "Build Story Web (WASM)" step:

1. **`getrandom` 0.2 missing the `js` feature** (current failure): `rand
0.8` (via `fake` in `gpui-component-story`) pulls in `getrandom` 0.2,
which hits a `compile_error!` on wasm32-unknown-unknown unless the `js`
feature is enabled. The dependency that used to enable it through
feature unification was dropped in the GPUI upgrade (#2573). Now the
feature is enabled explicitly for wasm targets in
`crates/story/Cargo.toml`.

2. **`wasm-bindgen-cli` version mismatch** (failure on the July 13 run):
the workflow installed a hardcoded CLI 0.2.118 while Cargo.lock has
`wasm-bindgen` 0.2.121. The version is now read from Cargo.lock so they
stay in sync.

Verified locally: `cargo check --target wasm32-unknown-unknown` in
`crates/story-web` passes.

> This PR is AI-generated (Claude Code) and human-reviewed.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-authored-by: Claude Fable 5 <noreply@anthropic.com>