fix: resolve merge conflicts with main (R + ObjC) (docs check acknowledged)

Resolved merge with origin/main (44a3505 R extractor). Combined both
ObjC and R additions to:
- crates/codegraph-core/src/file_collector.rs SUPPORTED_EXTENSIONS
  (keep both 'm' and 'r'/'R')
- crates/codegraph-core/src/parser_registry.rs LanguageKind::all()
  (keep ObjC and R in declaration order)
- Bumped EXPECTED_LEN from 30 to 31 to match the new variant count.
- tests/parsers/native-drop-classification.test.ts: decrement the
  unsupported-by-native count from 6 to 5 since the merge correctly
  removed 'src/k.m' from the input array (ObjC is now natively
  supported) but main's side of the conflict left the old count.

This is a merge resolution — no new features, no doc changes needed
(ObjC language support docs were already added in an earlier commit
on this branch; R docs landed on main with #1102).

Author: carlos-alm

Cargo.lock

@@ -40,6 +40,7 @@ tree-sitter-objc = "3"
 tree-sitter-julia = "0.23"
 tree-sitter-clojure-orchard = "0.2"
 tree-sitter-erlang = "0.16"
+tree-sitter-r = "1.2"
 tree-sitter-solidity = "1.2"
 rayon = "1"
 ignore = "0.4"

crates/codegraph-core/Cargo.toml

@@ -417,6 +417,17 @@ pub const ERLANG_AST_CONFIG: LangAstConfig = LangAstConfig {
     string_prefixes: &[],
 };
 
+pub const R_AST_CONFIG: LangAstConfig = LangAstConfig {
+    new_types: &[],
+    throw_types: &[],
+    await_types: &[],
+    // tree-sitter-r emits `string` for both single- and double-quoted literals.
+    string_types: &["string"],
+    regex_types: &[],
+    quote_chars: &['\'', '"'],
+    string_prefixes: &[],
+};
+
 pub const SOLIDITY_AST_CONFIG: LangAstConfig = LangAstConfig {
     new_types: &["new_expression"],
     throw_types: &["revert_statement"],

crates/codegraph-core/src/extractors/helpers.rs

@@ -20,6 +20,7 @@ pub mod objc;
 pub mod ocaml;
 pub mod php;
 pub mod python;
+pub mod r_lang;
 pub mod ruby;
 pub mod rust_lang;
 pub mod scala;
@@ -147,6 +148,9 @@ pub fn extract_symbols_with_opts(
         LanguageKind::Erlang => {
             erlang::ErlangExtractor.extract_with_opts(tree, source, file_path, include_ast_nodes)
         }
+        LanguageKind::R => {
+            r_lang::RExtractor.extract_with_opts(tree, source, file_path, include_ast_nodes)
+        }
         LanguageKind::Solidity => {
             solidity::SolidityExtractor.extract_with_opts(tree, source, file_path, include_ast_nodes)
         }