cargo-chef prepare injects per-target `edition` causing deprecation warnings with edition 2024

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## Description

When using `cargo chef prepare` on a project with `edition = "2024"` in `[package]`, the generated recipe injects `edition = "2024"` onto each individual target (`[[bin]]`, `[lib]`, `[[example]]`). This triggers deprecation warnings from Cargo nightly:

```
warning: /build/crates/mt-tauri/Cargo.toml: `edition` is set on library `mt_lib` which is deprecated
warning: /build/crates/mt-tauri/Cargo.toml: `edition` is set on binary `mt` which is deprecated
warning: /build/crates/mt-tauri/Cargo.toml: `edition` is set on example `audio_test` which is deprecated
```

## Reproduction

`Cargo.toml`:
```toml
[package]
name = "my-crate"
edition = "2024"

[[bin]]
name = "my-bin"
path = "src/main.rs"

[lib]
name = "my_lib"
```

Run `cargo chef prepare --recipe-path recipe.json` and inspect the generated manifest — each target gets an explicit `edition = "2024"` field.

## Expected behavior

cargo-chef should not propagate the package-level `edition` to individual targets, since Cargo 2024 edition inherits it automatically from `[package]`.

## Environment

- cargo-chef: 0.1.77
- Rust: nightly-2026-02-09
- edition: 2024

Start at the manifest generation used by `cargo chef prepare` and reproduce the issue with the provided `Cargo.toml` and `--recipe-path recipe.json`. Confirm that generated `[[bin]]`, `[lib]`, and `[[example]]` entries no longer contain propagated `edition` fields, and that the Cargo deprecation warnings are gone.

Written by the indexing model from the issue text.