style: introduce rustfmt.toml

[AsakuraMizu]

Tracking issue: #25

[Copilot]

Pull request overview

Introduces a repository-wide rustfmt.toml and reformats existing Rust sources to match the new formatting/import style across supported architectures.

Changes:

• Add a rustfmt.toml with customized formatting/import rules (incl. comment normalization and enum discriminant alignment).
• Reformat imports to use nested use ... { ... } style and adjust blank lines for consistency.
• Apply rustfmt-driven style updates in trap/context/uspace/asm modules across x86_64, riscv, arm/aarch64, and loongarch64.

Reviewed changes

Copilot reviewed 18 out of 20 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
src/x86_64/uspace.rs	Import spacing adjusted to match new formatting rules.
src/x86_64/syscall.rs	Imports regrouped into a nested use x86_64::{...} block.
src/x86_64/mod.rs	Consolidates and formats re-exports into a single grouped pub use self::{...}.
src/x86_64/init.rs	Reformats re-exports into grouped pub use super::{...}.
src/x86_64/idt.rs	Regroups x86_64 imports into a nested block.
src/x86_64/gdt.rs	Regroups x86_64 imports into a nested block.
src/x86_64/context.rs	Adds spacing between std/core and external imports per rustfmt.
src/trap.rs	Reorders/reformats public re-exports (linkme + MappingFlags).
src/riscv/uspace.rs	Reorders imports and simplifies cfg’d statement formatting.
src/riscv/trap.rs	Regroups riscv imports into a nested block.
src/riscv/context.rs	Spacing changes; comment normalization in a match arm.
src/riscv/asm.rs	Regroups riscv imports into a nested block.
src/loongarch64/context.rs	Adds blank line after cfg import.
src/arm/trap.rs	Aligns enum discriminants (spacing) per rustfmt config.
src/arm/init.rs	Import ordering/spacing adjusted.
src/arm/context.rs	Consolidates core imports into use core::{...} and adds spacing.
src/arm/asm.rs	Reorders imports to match grouping rules.
src/aarch64/trap.rs	Aligns enum discriminants (spacing) per rustfmt config.
src/aarch64/context.rs	Consolidates core imports into use core::{...} and adds spacing.
rustfmt.toml	New rustfmt configuration driving the formatting changes.

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