Fix the build: pin nightly-2022-11-02, repair CI, fix onboarding docs

[jenish-25]

Summary

The project currently fails to build for everyone on a modern toolchain
(see #35, #36, #37). This PR revives the build and fixes developer onboarding.

Root cause: the crate relies on nightly-only feature gates
(#![feature(async_closure)], #![feature(mutex_unlock)] in
tinydancer/src/main.rs) and locked, era-specific dependencies, but nothing pins
a compatible toolchain. A current nightly can't compile the locked
proc-macro2 1.0.51 (unknown feature proc_macro_span_shrink) and has removed
mutex_unlock entirely, so the build dies before it starts. CI made this worse
by installing no system dependencies and using archived actions-rs/* actions.

Changes

• Add rust-toolchain.toml pinning nightly-2022-11-02 — the same nightly the
  diet-rpc-validator Solana fork (which this crate builds against) uses in its
  ci/rust-version.sh. rustup now selects the correct compiler automatically.
• Repair .github/workflows/crates.yml: install the required system deps
  (protobuf-compiler, libudev-dev, libssl-dev, clang, cmake, …), pin the
  toolchain, move to ubuntu-22.04, modernize to actions/checkout@v4 +
  dtolnay/rust-toolchain, fix the malformed branch: trigger (→ branches:),
  add pull_request / workflow_dispatch, and disable the crates.io publish job
  (a maintainer-only action).
• README: fix the cargo install command (the old half-baked-client repo now
  redirects), document the pinned toolchain, and list the Linux system deps.
• Bump tinydancer to 0.0.9.

Verification

Built cleanly on GitHub Actions (Ubuntu, nightly-2022-11-02):

• Before (fails on proc-macro2): https://github.com/jenish-25/tinydancer/actions/runs/28919854760
• After (green, full release build): https://github.com/jenish-25/tinydancer/actions/runs/28921014517

Closes #35, #36, #37.