feat(extraction): add Visual Basic .NET language support (.vb) (#648, #639, #170) (#1164)

Vendored patched govindbanura/tree-sitter-vbnet grammar (MIT, ~20-fix patch
+ new external scanner for XML literals and multi-line LINQ continuation;
provenance + rebuild instructions in docs/grammars/tree-sitter-vbnet.md),
vbnet extractor with VB-specific call/index disambiguation, Inherits/
Implements heritage, As New instantiation, events, Declare P/Invoke, and
MustOverride abstract members.

Parse health on five real repos: PolicyPlus 100%, CompactGUI 100%,
staxrip 95.2%, SCrawler 87.2%, PCL 87.5% (upstream grammar: 3-18%).
Retrieval A/B (sonnet): 26-43% faster with 0-5 file reads vs 7-20 without.

Co-authored-by: Claude Fable 5 <noreply@anthropic.com>

src/extraction/grammars.ts

@@ -43,6 +43,7 @@ const WASM_GRAMMAR_FILES: Record<GrammarLanguage, string> = {
   cfscript: 'tree-sitter-cfscript.wasm',
   cfquery: 'tree-sitter-cfquery.wasm',
   cobol: 'tree-sitter-cobol.wasm',
+  vbnet: 'tree-sitter-vbnet.wasm',
 };
 
 /**
@@ -131,6 +132,9 @@ export const EXTENSION_MAP: Record<string, Language> = {
   '.cob': 'cobol',
   '.cobol': 'cobol',
   '.cpy': 'cobol',
+  // VB.NET: vendored grammar (patched govindbanura/tree-sitter-vbnet) — classes,
+  // modules, interfaces, structures, properties, events, Handles clauses, LINQ.
+  '.vb': 'vbnet',
   // Spring config: `application.properties` / `application-*.properties`. Same
   // shape as the `.yml` variants — the YAML/properties extractor emits one node
   // per leaf key, and the Spring resolver links `@Value("${k}")` references.
@@ -249,7 +253,7 @@ export async function loadGrammarsForLanguages(languages: Language[]): Promise<v
       // `class Foo(...)` as an ERROR that swallows the whole class (#237); we
       // vendor the upstream ABI-15 tree-sitter-c-sharp 0.23.5 wasm, which parses
       // primary constructors natively.
-      const wasmPath = (lang === 'pascal' || lang === 'scala' || lang === 'lua' || lang === 'luau' || lang === 'csharp' || lang === 'r' || lang === 'cfml' || lang === 'cfscript' || lang === 'cfquery' || lang === 'cobol')
+      const wasmPath = (lang === 'pascal' || lang === 'scala' || lang === 'lua' || lang === 'luau' || lang === 'csharp' || lang === 'r' || lang === 'cfml' || lang === 'cfscript' || lang === 'cfquery' || lang === 'cobol' || lang === 'vbnet')
         ? path.join(__dirname, 'wasm', wasmFile)
         : require.resolve(`tree-sitter-wasms/out/${wasmFile}`);
       const language = await WasmLanguage.load(wasmPath);
@@ -468,6 +472,7 @@ export function getLanguageDisplayName(language: Language): string {
     cfscript: 'CFScript',
     cfquery: 'CFQuery (SQL)',
     cobol: 'COBOL',
+    vbnet: 'Visual Basic .NET',
     unknown: 'Unknown',
   };
   return names[language] || language;