Remove most Datetime panic paths

[williampMSFT]

This change removes most panic paths from the Datetime type. Doing this required a breaking interface change to how months are expressed. Additionally, it adds some tests that exercise every date for the next couple hundred years to catch any date-specific bugs.

There are still a couple expects() in the chrono conversion path because we know about some invariants that the compiler can't really know about, but those are all behind a feature flag. I don't see a path to removing these without either using some sort of unsafe code or making an operation that is infallible have a fallible API. Compatibility with the chrono lib is behind a feature flag, though, so panic-sensitive clients can opt to not enable the chrono feature.

[Copilot]

Pull request overview

This PR refactors the Datetime type to eliminate most panic paths by introducing a type-safe Month enum and removing array indexing operations. The changes improve code safety for embedded systems where panics can be catastrophic, while maintaining strict validation through comprehensive testing that exercises every date from 1970 to 2500.

Key changes:

• Introduced Month enum with type-safe month representation (1-12) using num_enum for conversions
• Replaced panic-prone array indexing with const methods on the Month enum
• Added clippy lints to warn against panic-inducing operations (expect_used, unwrap_used, panic, etc.)

Reviewed changes

Copilot reviewed 4 out of 7 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
supply-chain/imports.lock	Added rustversion audit entries for dependency chain verification
supply-chain/audits.toml	Added audits for num_enum, num_enum_derive, and rustversion dependencies
embedded-mcu-hal/Cargo.toml	Added num_enum dependency and clippy lints to prevent panics
Cargo.lock	Updated with num_enum and rustversion dependency entries
embedded-mcu-hal/src/time/mod.rs	Exported the new Month enum publicly
embedded-mcu-hal/src/time/datetime.rs	Replaced u8 month with Month enum, removed array-based month logic, updated all tests to use Month enum, added comprehensive date roundtrip test
embedded-mcu-hal/src/lib.rs	Whitespace formatting changes only

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[felipebalbi]

LGTM, just line endings on one file again.