cargo-miden 0.8.1 fails to install on all toolchains + cross-component WIT circular dependency + version compatibility table request

### Packages versions

cargo-miden: 0.8.1 (fails to install)
miden-client: 0.14.7
rustc nightly: 1.92.0-nightly (nightly-2025-09-30)
rustc stable: 1.87.0
OS: Linux WSL2 (Windows 11)

### Bug description

We are building GhostMate, an agent chess game
on Miden (ghostmate.vercel.app).
Redirected here by @SantiagoPittella from
0xMiden/miden-client#2168.

PROBLEM 1 cargo-miden 0.8.1 fails on every toolchain

On nightly-2025-09-30 (rustc 1.92.0-nightly):
cargo +nightly install cargo-miden --locked fails with:
"cannot specialize on trait Copy" in hashbrown-0.15.5

On stable rustc 1.87.0:
cargo +stable install cargo-miden --locked fails with:
"#![feature] may not be used on stable release channel"

cargo miden --version returns "no such command: miden"
on every toolchain tried.

The root cause appears to be that cargo-miden 0.8.1
lockfile pins hashbrown 0.15.5 which uses the
specialization nightly feature currently broken
on nightly-2025-09-30 and not allowed on stable.

There is no documented pinned nightly that
cargo-miden 0.8.1 is known to build on, and no
rust-toolchain.toml ships with it.

Q: What is the exact install command and toolchain
version that produces a working cargo miden binary today?

---

PROBLEM 4 Cross-component WIT circular dependency

Our note scripts call functions on account contracts
via cross-component WIT bindings:

move-note cannot be built until game-contract WIT
is generated (game-contract must be built first).
But game-contract embeds move-note MAST root as a
compile-time constant only known after move-note
is built.

This is a genuine circular dependency with no
documented resolution pattern.

Q: Is there an official pattern for breaking this
circular dependency? For example:
- Can cargo miden build --all resolve dependency
order automatically?
- Can note scripts call account components without
embedding a WIT path?
- Can MAST roots be read from build artifacts at
deploy time instead of compile-time constants?

COMPATIBILITY TABLE REQUEST

There is no published compatibility matrix between:
- miden SDK version
- miden-client version
- cargo-miden version
- Required Rust toolchain

Q: Can a version compatibility table be added
to the docs showing which versions work together?

Example of what would help:
miden-client 0.14.x → stable Rust 1.93+
cargo-miden 0.8.1 → ??? (currently uninstallable)
miden SDK 0.12 → compatible with client 0.14?
testnet → v0.14

### How can this be reproduced?

# Problem 1 cargo-miden uninstallable on nightly
rustup toolchain install nightly-2025-09-30
cargo +nightly install cargo-miden --locked
# fails: hashbrown specialization error

# Problem 1 cargo-miden uninstallable on stable
cargo +stable install cargo-miden --locked
# fails: #![feature] on stable channel

# Verify no working binary exists
cargo miden --version
# returns: error: no such command: miden

# Problem 4 cross-component WIT
git clone https://github.com/AQEELERRHH/ghostmate
cd ghostmate/contracts/move-note
cargo build
# fails: game-contract/target/generated-wit missing

### Relevant log output

```shell
# Problem 1 nightly
error: cannot specialize on trait `Copy`
--> hashbrown-0.15.5/src/raw/mod.rs:3269:9
|
3269 | impl RawTableClone for RawTable {
| ^^^^
error: could not compile `hashbrown` (lib)
error: failed to compile `cargo-miden v0.8.1`

# Problem 1 stable
error[E0554]: `#![feature]` may not be used on
the stable release channel
--> hashbrown-0.15.5/src/lib.rs:15:5
error: cannot specialize on trait `Copy`
error: failed to compile `cargo-miden v0.8.1`

# Problem 4 cross-component WIT
error: failed to process WIT for dependency
'miden:game-contract': no WIT world definition
found in directories
'[ghostmate/contracts/game-contract/target/generated-wit]'

error[E0433]: failed to resolve: could not find
`bindings` in the crate root
--> src/lib.rs:17:12
|
17 | use crate::bindings::miden::game_contract::game_contract;
| ^^^^^^^^ could not find `bindings` in crate root
```

The issue describes three problems: cargo-miden installation failures due to hashbrown dependency, a circular dependency in WIT bindings for cross-component calls, and a request for a version compatibility table. Start by examining the cargo-miden crate's Cargo.toml and lockfile to understand the hashbrown pin. For the WIT circular dependency, look at the build scripts and generated WIT directories in the ghostmate repository. 'Done' means identifying the exact toolchain that works, proposing a fix for the circular build, and drafting a compatibility matrix for the docs.

索引モデルが issue の本文から書いたものです。