feat(lang): add C and C++ language support (#2746)

## Summary
- Add tree-sitter-based C and C++ language implementations for
maintainability analysis (complexity, duplication, nested control flow,
etc.)
- Wire up tree-sitter dependencies, language registration in
`ALL_LANGS`, file type/extension mappings, and protobuf enum mappings
- Add integration test fixtures and test registration for both C and C++

## Test plan
- [x] Unit tests pass for both C and C++ language modules (11 tests)
- [x] Integration tests pass for both `c_tests` and `cpp_tests`
- [x] `cargo check` passes cleanly
- [ ] CI passes

🤖 Generated with [Claude Code](https://claude.com/claude-code)

---------

Co-authored-by: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
Co-authored-by: marschattha <arslan_21@rocketmail.com>

Author: 3 people

Cargo.lock

@@ -127,6 +127,8 @@ tracing-appender = "0.2.3"
 tracing-subscriber = { version = "0.3.20", features = ["env-filter"] }
 tracing-test = "0.2.5"
 tree-sitter = "0.22.6"
+tree-sitter-c = "0.21"
+tree-sitter-cpp = "0.21"
 tree-sitter-c-sharp = "0.21.3"
 tree-sitter-go = "0.21.2"
 tree-sitter-java = "0.21.0"

Cargo.toml

@@ -35,6 +35,8 @@ tempfile.workspace = true
 time.workspace = true
 tracing.workspace = true
 tree-sitter.workspace = true
+tree-sitter-c.workspace = true
+tree-sitter-cpp.workspace = true
 tree-sitter-c-sharp.workspace = true
 tree-sitter-go.workspace = true
 tree-sitter-java.workspace = true

qlty-analysis/Cargo.toml

@@ -3,6 +3,8 @@ use core::fmt;
 use std::sync::Arc;
 use tree_sitter::{Node, Parser, Query};
 
+mod c;
+mod cpp;
 mod csharp;
 mod go;
 mod java;
@@ -18,8 +20,8 @@ mod typescript;
 mod typescript_common;
 
 pub use {
-    csharp::*, go::*, java::*, javascript::*, kotlin::*, php::*, python::*, ruby::*, rust::*,
-    swift::*, tsx::*, typescript::*,
+    c::*, cpp::*, csharp::*, go::*, java::*, javascript::*, kotlin::*, php::*, python::*, ruby::*,
+    rust::*, swift::*, tsx::*, typescript::*,
 };
 
 #[allow(clippy::borrowed_box)]
@@ -32,6 +34,8 @@ use lazy_static::lazy_static;
 lazy_static! {
     pub static ref ALL_LANGS: Vec<Box<dyn Language + Sync>> = {
         vec![
+            Box::<c::C>::default(),
+            Box::<cpp::Cpp>::default(),
             Box::<csharp::CSharp>::default(),
             Box::<php::Php>::default(),
             Box::<kotlin::Kotlin>::default(),