Various improvements in all parts

[thomasw04]

• I2C and SPI error handling.
• Scheduler fixes
• and more

[xarantolus]

Mostly looked at CAN, seems fine

[Copilot]

Pull request overview

This PR refines several kernel and HAL subsystems, primarily standardizing device-driver error handling around POSIX errno values and adjusting scheduler real-time semantics (deadlines/budget handling).

Changes:

• Standardize SPI/I2C/CAN HAL interfaces to return -PosixError_* and update Rust wrappers to convert C return codes via ok_or_err.
• Add I2C transfer timeouts and bus recovery support end-to-end (C interface → Rust HAL → kernel driver API).
• Update RT scheduling to use relative deadlines and new replenishment behavior; add a default thread finalizer when none is supplied.

Reviewed changes

Copilot reviewed 30 out of 30 changed files in this pull request and generated 6 comments.

Show a summary per file

File	Description
src/uapi/spi.rs	Removes unused import in SPI uAPI wrapper.
src/uapi/i2c.rs	Removes unused import in I2C uAPI wrapper.
src/uapi/sched.rs	Tightens RT attribute validation (deadline vs budget/period).
src/types/queue.rs	Switches queue APIs to kernel Result/kerr! errno-style errors and updates tests.
src/types.rs	Exposes the queue module from types.
src/syscalls/sched.rs	Validates RT attributes in the syscall boundary before creating threads.
src/sched/thread.rs	Adds relative deadlines and changes RT server budget/deadline accounting.
src/sched/task.rs	Adds a default thread finalizer when no finalizer is provided.
src/sched/rt.rs	Changes EDF enqueue/put/pick behavior to align with new RT server fields.
src/sched.rs	Adds thread_finalizer used as the default thread finalizer.
src/lib.rs	Re-exports HAL API error module items at crate root.
src/error.rs	Updates WARN macros to use kprintln! and keeps errno/error helpers.
src/drivers/spi.rs	Makes SPI bus list push fallible via expect, and minor logging tweak.
src/drivers/i2c.rs	Adds timeouts + bus recovery API to I2C driver; changes bus list push to expect.
src/drivers/can.rs	Switches CAN driver error type to PosixError and adjusts exports.
machine/cortex-m/st/stm32l4/interface/spi.c	Adds errno-mapped SPI error handling, busy-wait timeout, and better validation/timeout calc.
machine/cortex-m/st/stm32l4/interface/i2c.c	Adds errno-mapped I2C errors, per-transfer timeout, and bus recovery helpers.
machine/cortex-m/st/stm32l4/interface/gpio.h	Declares new open-drain output GPIO init helper.
machine/cortex-m/st/stm32l4/interface/gpio.c	Implements gpio_init_output_od.
machine/cortex-m/st/stm32l4/interface/export.h	Extends I2C transfer struct with timeout + new recovery function declarations.
machine/cortex-m/st/stm32l4/interface/can.c	Converts CAN interface to POSIX errno returns with improved validation/mapping.
machine/cortex-m/src/stub/i2c.rs	Updates stub signatures for timeouts and adds stub bus recovery APIs.
machine/cortex-m/src/stub/can.rs	Converts stub CAN errors to PosixError.
machine/cortex-m/src/native/spi.rs	Uses ok_or_err to map SPI C return codes into PosixError.
machine/cortex-m/src/native/sched.rs	Cleans up unused Range import.
machine/cortex-m/src/native/i2c.rs	Adds timeout field plumbing + bus recovery wrappers; uses ok_or_err.
machine/cortex-m/src/native/can.rs	Uses ok_or_err and maps CAN C return codes into PosixError.
machine/cortex-m/build.rs	Generates a C header (hal_api.h) for PosixError via cbindgen and includes it in HAL builds.
machine/api/src/lib.rs	Moves POSIX error definitions into a dedicated error module and re-exports them.
machine/api/src/error.rs	New module containing PosixError, Result, and helper conversion functions.

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