Publish all crates: rain-metadata-bindings + rain-metaboard-subgraph

[thedavidmeister]

Only `rain-metadata` is published on crates.io today (latest `0.0.2-alpha.6`). The other two workspace crates are not:

crate	on crates.io?
`rain-metadata`	✅
`rain-metadata-bindings`	❌
`rain-metaboard-subgraph`	❌

Downstream consumers (rain.interpreter, rain.flare, st0x.deploy chain) need these as crates.io deps once they drop their own git/submodule equivalents.

Scope

1. Add description + repository fields to `crates/bindings/Cargo.toml` and `crates/metaboard/Cargo.toml` so crates.io accepts them without warnings.
2. Verify each crate's `cargo publish --dry-run` succeeds in isolation (no git path deps, etc.).
3. Extend `.github/workflows/manual-rs-release.yml` (or split into a per-crate release flow) to bump + publish all three crates in topological order: bindings first, then metadata + metaboard which depend on it.
4. Run the release once to bring all three to a current version on crates.io.