Add rustfmt configuration and reformat code

- Document new Rust formatting standards in AGENTS, CODE_MAP, and
  PROGRESS.
- Add rustfmt.toml with style 2024, 2‑space indents, 100‑char width, LF
  endings.
- Apply consistent 2‑space indentation and ordering across source files.
- Minor clean‑up of imports and whitespace to match the new style.

rustfmt.toml

@@ -0,0 +1,11 @@
+edition = "2024"
+style_edition = "2024"
+
+max_width = 100
+hard_tabs = false
+tab_spaces = 2
+newline_style = "Unix"
+
+reorder_imports = true
+reorder_modules = true
+use_small_heuristics = "Default"