Publish shuttle-tokio as 1.0.0

[sarsko]

The wrappers mirror the version of the crate they wrap, so that a downstream crate can depend on the wrapper using the same version requirement it would have used for the real crate:

Wrapper	Version	Wraps
shuttle-parking_lot	0.12.5	parking_lot 0.12
shuttle-dashmap	6.1.0	dashmap 6.1
shuttle-lazy_static	1.5.0	lazy_static 1.5
shuttle-rand	0.8.6	rand 0.8.6
shuttle-async-stream	0.3.6	async-stream 0.3.6
shuttle-tokio-util	0.7.0	tokio-util 0.7
shuttle-tokio-retry	0.3.0	tokio-retry 0.3
shuttle-tokio	0.1.0	tokio 1.x

shuttle-tokio was the odd one out. It also made wrappers/README.md contradict itself, telling users to write version = "1" in two places and version = "0.1.0" in a third.

This bumps it to 1.0.0 so it follows the same scheme as its siblings, and fixes the one stale reference in wrappers/README.md so all three examples agree.

Notes for review

• This is a major version bump of an already-published crate — 0.1.0 is on crates.io. Under Cargo's rules 0.1.0 and 1.0.0 are separate incompatible lines, so anyone currently on version = "0.1" keeps resolving to 0.1.0 and is not broken by the release; they opt in by changing their requirement to 1.
• Nothing in this repository depends on shuttle-tokio. It is a leaf that only downstream users consume, so the change is contained to its own manifest. Verified with grep -rn 'package = "shuttle-tokio"' --include=Cargo.toml, which matches only its own [package] name.
• The shuttle-tokio README and crate docs use a VERSION_NUMBER placeholder rather than a literal, so they needed no change.
• shuttle-tokio-stream stays at 0.1.0: tokio-stream is itself 0.1.x, so it already matches the scheme.
• cargo check --workspace and cargo fmt --all -- --check clean with RUSTFLAGS=-Dwarnings.

No CHANGELOG entry, matching the convention that release-prep PRs aggregate them.

Relation to other open PRs

• Add the shuttle_enabler crate #325 (shuttle_enabler) depends on this, since its dependency on shuttle-tokio needs the 1 requirement. It is stacked on this branch and will retarget to main automatically once this merges.
• Rewrite README to reflect the current state of Shuttle #326 (README rewrite) documents version = "1" on the strength of this change.

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By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.

[bkragl]

did we make a mistake in other wrappers?

like, shuttle-parking_lot is v0.12.5. seems like it should have been v0.12.0.