feat(extraction): add Solidity language support (.sol) (#374, #648) (#1170)

Contracts/libraries/interfaces, structs, enums, modifiers, events, errors,
state variables; call edges for emit/revert/modifier guards/base-constructor
chains/library calls; is-inheritance with implements reclassification;
import resolution. Validated on solmate, solady, openzeppelin-contracts.

Lands #667.

Co-authored-by: naiba <hi@nai.ba>
Co-authored-by: Claude Fable 5 <noreply@anthropic.com>

CHANGELOG.md

@@ -11,6 +11,7 @@ and adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
 ### New Features
 
+- CodeGraph now indexes **Solidity** (`.sol`) — contracts, libraries, interfaces, structs, enums, modifiers, events, errors, and state variables become first-class symbols, with call edges that follow `emit`, `revert`, modifier guards (`onlyOwner`-style, including base-constructor chains like `constructor() ERC20(...)`), and library/method calls (including `using` directives). `import` directives resolve to the imported file, so cross-contract questions like "trace `transferFrom` through allowance and balance updates" or "how does `onlyRole` reach the role storage?" work out of the box on real Solidity codebases (validated on solmate, solady, and OpenZeppelin Contracts). Thanks @naiba. (#374, #648)
 - Erlang behaviour dispatch is now followed through the graph: a framework call through a variable module — cowboy's `Handler:init`/`Middleware:execute` folds, a plugin manager's `Mod:callback(...)` — links to the repo's implementations of the behaviour that declares that callback, so flow traces and impact cross the OTP callback boundary instead of stopping at it. The links are precision-gated: the callback arity must match, exactly one behaviour may own that callback shape (a collision stays unlinked rather than guessed), the implementer must actually export the callback, and the fan-out is bounded — a behaviour with hundreds of implementers stays a visibly dynamic boundary. Every bridged hop is labeled as dynamic dispatch with its wiring site, never shown as a plain static call.
 - CodeGraph now indexes **Erlang** (`.erl`, `.hrl`) — functions, with clauses and arities of the same name grouped as one symbol spanning all of them, plus records with their fields, `-type`/`-opaque` aliases, `-define` macros, and `-spec` signatures attached to every function. Cross-module `mod:fn(...)` calls resolve to the target module's function, `fun name/arity` values are captured as references (so callback registrations like `lists:foreach(fun submit/1, ...)` link up), `-include`/`-include_lib` connect to the header files they pull in, `-behaviour` declarations link a callback module to its behaviour (and only ever to a module — a same-named macro or function elsewhere in the repo is never mistaken for one), and `-export` lists (plus `-compile(export_all)`) drive each function's public/private flag. OTP's indirection idioms are followed where the target is static: `spawn`/`apply`/`proc_lib`/`timer`/`rpc` calls that name their target as `(Module, Function, Args)` arguments produce call edges, and `gen_server:call`/`cast` connects to the target module's `handle_call`/`handle_cast` — its own when targeting `?MODULE` (including the `-define(SERVER, ?MODULE)` idiom), and the named module when a registered name follows OTP's name-the-server-after-its-module convention (`gen_server:call(other_mod, ...)`, directly or through a `-define(STORE, other_mod)` macro); a registered name that matches no module stays unlinked. Macros participate in the graph too: a `-define` body's calls belong to the macro, each `?MACRO(...)` use site links into the call chain (and bare `?CONSTANT` reads are tracked as references), so a call path hidden behind a macro — `set_password → ?SQL_UPSERT_T → sql_query_t` — traces end-to-end and "where is this macro used" is answerable. escripts index like any module (the shebang line is understood), and OTP application resource files (`.app.src`, `.app`) join the graph: `{mod, ...}` links an app to its callback module and `{applications, [...]}` connects umbrella sibling apps — resolving only ever to modules, so an OTP app name like `ssl` is never mistaken for a same-named function. Truly dynamic dispatch (`Mod:handle(...)`, message sends, var-module spawns) is deliberately left unlinked rather than guessed. `codegraph_explore` also understands Erlang-native symbol spelling in queries — `mod:fn/3` and `init/2` find the symbols they name. (#635, #648)
 - CodeGraph now indexes **Visual Basic .NET** (`.vb`) — classes, Modules, interfaces, structures, enums, properties, events, `MustOverride` abstract members, and `Declare` P/Invoke signatures, with `Inherits`/`Implements` hierarchy edges, call edges (resolved through VB's ambiguous call-vs-index parentheses), and `New`/`As New` instantiation links. Real-world VB styles parse cleanly: WinForms designer files, interpolated and multi-line strings, XML literals (embedded `<%= %>` expressions included), single-line and multi-line LINQ queries, multi-line lambdas, `Handles`/`WithEvents` event wiring, Custom Events, date literals, classic type-character identifiers (`i%`, `name$`), and non-English (Unicode) identifiers. (#648, #639, #170)