Enforce stricter rustfmt rules to prevent style ambiguity

Changes:
- `match_arm_leading_pipes`: "Preserve" -> "Never" (enforce single style)
- `trailing_semicolon`: false -> true (enforce `return 42;` with semicolon)
- Add `normalize_comments = true` (normalize comment spacing)
- Add `normalize_doc_attributes = true` (enforce `///` over `#[doc = ""]`)

These changes ensure only one valid formatting style exists, reducing
unnecessary diffs in pull requests caused by different but valid styles.

Author: pgherveou

.rustfmt.toml

@@ -8,16 +8,18 @@ imports_granularity = "Crate"
 reorder_imports = true
 # Consistency
 newline_style = "Unix"
+normalize_comments = true
+normalize_doc_attributes = true
 # Misc
 chain_width = 80
 spaces_around_ranges = false
 binop_separator = "Back"
 reorder_impl_items = false
-match_arm_leading_pipes = "Preserve"
+match_arm_leading_pipes = "Never"
 match_arm_blocks = false
 match_block_trailing_comma = true
 trailing_comma = "Vertical"
-trailing_semicolon = false
+trailing_semicolon = true
 use_field_init_shorthand = true
 # Format comments
 comment_width = 100