feat(extraction): add VB.NET language support - #1

Adds VB.NET (.vb) indexing to codegraph — classes, modules, structures, interfaces, enums, Subs/Functions, properties, constants, and Imports, with call, instantiation, and inheritance edges that resolve across files.

Grammar

Vendors a locally-patched build of CodeAnt-AI/tree-sitter-vb-dotnet (MIT). The upstream 0.1.x grammar produced ERROR trees on ordinary VB; the patches close generic (Of T) declarations, separate-line Inherits/Implements, member-level Implements/Handles, New Foo(args), the As New shorthand, nested types, #Region, Enum As <type>, For Each typed loop vars, Dim array declarators, attributes, ?. null-conditional access, and implicit line continuation inside () / after binary operators. Full patch set, rebuild steps, and a real-world status writeup live in docs/grammars/vbnet/.

Extractor (src/extraction/languages/vbnet.ts)

• resolveBody hook so call/reference extraction reaches inline method bodies (VB declarations have no body field); extractStruct now consults it too, so structures extract.
• visitNode hook emitting extends/implements edges from the line-statement Inherits/Implements clauses the core's field-based extractor can't see.
• With-receiver inference: leading-dot calls (With obj … .Member) are qualified with the inferred receiver type via a new general resolveCallName extractor hook, or dropped when the type is unknown — never a bare, mis-resolving ref.

Resolver

A callable-aware VB-intrinsics filter (UBound, Len, CInt, …) drops stray edges where an intrinsic name-matches a non-callable user symbol, while leaving genuine user methods resolvable. Const fields are classified as constant kind.

Validation

Indexed a real 1,146-file VB.NET codebase: ~53k call edges (~40k cross-file), 555 inheritance edges, no node explosion, ~14s to index. A with/without A/B on a cross-assembly trace had codegraph answer in 1 command / 0 file reads vs the baseline's 11 greps. New parameterized extraction tests cover detection, structure, inheritance, intrinsics filtering, continuation, and With-receiver inference; full suite green (1,588 passing).

Status & known gaps

Support is experimental — the vendored grammar is young, so method-body control flow can parse incompletely on some files (the class/method structure and most call edges still extract). Remaining gaps (documented in docs/grammars/vbnet/README.md): leading-dot method chains and assignment/return continuations are unparsed (~34% of files parse fully clean, though extraction holds up well past that via local error recovery); multi-namespace Imports A, B keeps only the first; no VB framework resolvers yet.

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