improve fmt and related just commands

[nyurik]

• consolidated just fmt will format using nightly (preferred) or regular cargo fmt. This is identical to what we had before as just fmt2
• remove unused rustfmt.toml
• reformatted everything

[Copilot]

Pull Request Overview

Consolidates and simplifies formatting targets, removes unused config, and applies consistent reformatting across the codebase.

• Deletes obsolete rustfmt.toml
• Merges nightly and stable cargo fmt into one just fmt recipe (with fallback)
• Reorders and combines imports in modules for a consistent style

Reviewed Changes

Copilot reviewed 13 out of 13 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
rustfmt.toml	Removed unused rustfmt configuration
martin/src/styles/mod.rs	Reordered use statements
martin/src/srv/styles.rs	Consolidated Actix imports and moved StyleSources import
martin/src/sprites/mod.rs	Combined collection imports
martin/src/source.rs	Moved HashMap import to file top
martin/src/pmtiles/mod.rs	Split AWS S3 imports onto separate lines
martin/src/fonts/mod.rs	Removed duplicated HashMap import
martin/src/cog/source.rs	Reordered test use statements
martin/src/cog/model.rs	Split tiff imports
martin/src/args/root.rs	Simplified clap imports
justfile	Updated formatting/checking recipes (fmt, test-fmt), removed --unsorted from default

Comments suppressed due to low confidence (1)

martin/src/pmtiles/mod.rs:13

• [nitpick] For brevity and consistency, you could combine these two imports into use pmtiles::aws_sdk_s3::{Client as S3Client, config::Builder as S3ConfigBuilder};.

use pmtiles::aws_sdk_s3::Client as S3Client;

[CommanderStorm]

Nice, thanks