cargo-workspace: cascaded dependent bumps ignore the active prerelease window

## What happens

When a cargo workspace is in a prerelease window (a `PrereleaseVersioningStrategy`, e.g. `prerelease: true` with `prereleaseType: "beta"`), crates that are released directly get the correct prerelease bump (`1.0.0-beta.0` → `1.0.0-beta.1`).

But a crate that is only **cascade-bumped** - i.e. it has no release commits of its own and is force-bumped solely because it depends on a crate that *is* being released - gets the wrong version. Instead of incrementing the prerelease counter, it bumps the base patch and keeps the stale prerelease suffix:

```
1.0.0-beta.0 → 1.0.1-beta.0 ❌ (expected: 1.0.0-beta.1)
```

So in a single release PR you end up with two inconsistent paths:

- `core/*` (directly released) → `1.0.0-beta.1` ✅
- `bindings/*` (only a dependent of `core`) → `1.0.1-beta.0` ❌

## Root cause

`CargoWorkspace.bumpVersion` always uses a raw `PatchVersionUpdate`, which is unaware of the configured versioning strategy:

src/plugins/cargo-workspace.ts

```ts
protected bumpVersion(pkg: CrateInfo): Version {
const version = Version.parse(pkg.version);
return new PatchVersionUpdate().bump(version);
}
```

`PatchVersionUpdate.bump` increments `patch` and carries the existing `preRelease` string through verbatim, which is exactly the `1.0.0-beta.0` → `1.0.1-beta.0` behavior above.

## This was already fixed for node-workspace

`node-workspace` had the identical bug and it was fixed in **#2249** (`fix: support-node-workspace-plugin-prerelease`, commit `88dc416`) by delegating to the configured strategy instead of hard-coding a patch bump:

```ts
protected bumpVersion(pkg: Package): Version {
const version = Version.parse(pkg.version);
const strategy = this.strategiesByPath[pkg.path];

if (strategy) return strategy.versioningStrategy.bump(version, []);
return new PatchVersionUpdate().bump(version);
}
```

`cargo-workspace` already stores `strategiesByPath` in `preconfigure()`, just like `node-workspace`, so the same one-line delegation applies directly.

## References

- node-workspace fix: #2249 (`88dc416`)

Start in src/plugins/cargo-workspace.ts, focusing on CargoWorkspace.bumpVersion and the strategiesByPath setup in preconfigure(). Compare the corresponding node-workspace fix in #2249, then verify that cascade-bumped crates advance the configured prerelease counter and no longer produce a stale suffix such as 1.0.1-beta.0.

Written by the indexing model from the issue text.