This commit introduces several enhancements to the Rust parsing and formatting capabilities:

1.  **Rust Parser Refactoring (`src/parser/lang/rust.rs`):**
    *   The Rust parser now extensively uses Tree-sitter queries for identifying and extracting code elements (functions, structs, enums, traits, impls, modules, attributes, visibility modifiers, documentation). This replaces much of the previous manual AST node traversal logic.
    *   Item-specific queries (`FUNCTION_QUERY`, `STRUCT_QUERY`, etc.) have been defined and integrated.
    *   A hybrid approach is used for attributes and visibility, combining query captures with existing helper functions to correctly handle both preceding and direct child elements.
    *   Documentation parsing continues to primarily use the `extract_documentation` helper, which identifies specific Rust doc comment patterns.

2.  **Enhanced Parser Unit Tests (`src/parser/lang/rust.rs`):**
    *   The existing parser test suite has been verified and significantly expanded.
    *   New fixture files (`fixtures/sample_advanced.rs`, `fixtures/empty.rs`, `fixtures/only_comments.rs`) were added.
    *   `fixtures/sample.rs` was heavily updated.
    *   New tests cover a wider range of scenarios, including complex generics, various attribute and documentation styles, different visibility modifiers (including `pub(in path)`), nested items, `extern crate`, `use` declarations, `mod` declarations, and edge cases like empty or comment-only files.
    *   Assertions have been made more granular.

3.  **Formatter Refinements (`src/parser/formatter/mod.rs`):**
    *   `TraitUnit` formatting for `Summary` and `NoTests` strategies now uses a more accurate head string (derived from `self.source` or `self.head` if it were present).
    *   The `Summary` strategy for `StructUnit` now correctly handles commas for fields, preventing double commas.
    *   Minor output trimming for cleaner formatting of files and modules.

4.  **New Formatter Unit Tests (`src/parser/formatter/rust.rs`):**
    *   A new test file dedicated to Rust formatters has been added.
    *   Tests include end-to-end scenarios (parsing fixture files then formatting the `FileUnit`) for all strategies.
    *   Specific tests verify the formatter refinements for `TraitUnit` heads and `StructUnit` field commas.
    *   Coverage includes various Rust constructs and formatting strategies.

**Note on Testing:**
Due to a build environment issue preventing `cargo test` execution, all test creation, updates, and verification were performed through manual code review and analysis of expected behavior.