Add I2c target traits

[felipebalbi]

Add both blocking and async versions of the I2c Target trait.

while at that also normalize line endings to LF only.

[github-actions]

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[Copilot]

Pull request overview

This PR introduces a new embedded_mcu_hal::i2c::target API that defines both blocking and async I²C target/slave traits, along with shared request/status/error types, and wires the new module into the crate and workspace dependencies.

Changes:

• Add i2c::target module with shared types (Request, statuses, error kinds) plus blocking::I2c and async::I2c traits.
• Expose a new top-level i2c module and add embedded-hal as a workspace dependency.
• Minor documentation link fixes in time and nvram, plus a .gitignore tweak.

Reviewed changes

Copilot reviewed 9 out of 11 changed files in this pull request and generated 5 comments.

Show a summary per file

File	Description
embedded-mcu-hal/src/time/mod.rs	Updates docs to reference unix_timestamp APIs.
embedded-mcu-hal/src/nvram.rs	Adds a missing intra-doc link target for storage.
embedded-mcu-hal/src/lib.rs	Exposes the new i2c module publicly.
embedded-mcu-hal/src/i2c/mod.rs	New I²C module root with re-exports and target submodule.
embedded-mcu-hal/src/i2c/target/mod.rs	Defines shared target-side request/status/error types and module docs.
embedded-mcu-hal/src/i2c/target/blocking.rs	Adds blocking I2c target trait.
embedded-mcu-hal/src/i2c/target/async.rs	Adds async I2c target trait and cancellation guidance.
embedded-mcu-hal/Cargo.toml	Adds embedded-hal dependency via workspace.
Cargo.toml	Defines embedded-hal in [workspace.dependencies].
Cargo.lock	Locks embedded-hal dependency.
.gitignore	Anchors target/ ignore to the repo root.

[jerrysxie]

Looks good, but some of the intended state transition might be tough to implement in hardware due to hardware feature that might auto advance state. After it is in, we should implement it on IMXRT and MCXA to see how it is.

[jerrysxie]

Looks good, but some of the intended state transition might be tough to implement in hardware due to hardware feature that might auto advance state. After it is in, we should implement it on IMXRT and MCXA to see how it is.

Create issue to implement these traits for mcxa and imxrt:

• imxrt: implement embedded-mcu i2c target trait embassy-imxrt#559
• mcxa: implement embedded-mcu i2c target trait embassy-mcxa#190