feat(extraction): add Erlang language support (.erl/.hrl) (#635, #648) (#1165)

Vendored WhatsApp/tree-sitter-erlang 0.19 (the ELP grammar, ABI 14) with an
Erlang-shaped extractor: multi-clause/multi-arity functions merged into one
symbol, -spec signatures, records with fields, -type/-opaque aliases, -define
macros, -include/-include_lib file edges, and -export-driven visibility.

Modules wrap in a namespace so remote mod:fn(...) calls resolve through the
existing qualified-name matcher as mod::fn with zero resolver changes.
-behaviour declarations link to the behaviour module — gated to namespace
targets only (bare-name fallthrough linked -behaviour(supervisor) to an
unrelated macro constant on emqx). OTP indirection with static targets is
followed: spawn/apply/proc_lib/timer/rpc MFA-argument callees, and
gen_server:call/cast(?MODULE | ?SERVER) to the module's own
handle_call/handle_cast. Var-module dispatch and message sends stay
deliberately unlinked. codegraph_explore also normalizes Erlang-native query
spelling (mod:fn/3, init/2) so named symbols resolve as typed.

Benchmarked on cowboy (189 files), ejabberd (414), emqx (2,447): extraction
PASS on all three; with-codegraph arms reached 2/2/0 file Reads vs 10/5+/19
without, fastest on the largest repo.

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

__tests__/explore-output-budget.test.ts

@@ -10,7 +10,7 @@ import { describe, it, expect, beforeAll, afterAll } from 'vitest';
 import * as fs from 'fs';
 import * as path from 'path';
 import * as os from 'os';
-import { getExploreOutputBudget, getExploreBudget, ToolHandler } from '../src/mcp/tools';
+import { getExploreOutputBudget, getExploreBudget, normalizeQuerySpelling, ToolHandler } from '../src/mcp/tools';
 import CodeGraph from '../src/index';
 
 describe('getExploreOutputBudget', () => {
@@ -254,3 +254,27 @@ describe('codegraph_explore output respects the adaptive budget', () => {
     expect(hasMethodBody).toBe(true);
   });
 });
+
+describe('normalizeQuerySpelling (Erlang mod:fn/arity)', () => {
+  it('rewrites Erlang-native symbol spellings to pipeline shapes', () => {
+    expect(normalizeQuerySpelling('cowboy_stream_h:request_process/3'))
+      .toBe('cowboy_stream_h.request_process');
+    expect(normalizeQuerySpelling('ejabberd_router:route/1 do_route/1 session'))
+      .toBe('ejabberd_router.route do_route session');
+    expect(normalizeQuerySpelling('init/2 handle_call/3')).toBe('init handle_call');
+  });
+
+  it('leaves query-language field prefixes and other spellings alone', () => {
+    expect(normalizeQuerySpelling('kind:function lang:erlang route'))
+      .toBe('kind:function lang:erlang route');
+    expect(normalizeQuerySpelling('path:src/api name:auth')).toBe('path:src/api name:auth');
+    expect(normalizeQuerySpelling('Foo::bar baz')).toBe('Foo::bar baz');
+    expect(normalizeQuerySpelling('https://example.com/docs')).toBe('https://example.com/docs');
+    expect(normalizeQuerySpelling('meeting at 12:30')).toBe('meeting at 12:30');
+    expect(normalizeQuerySpelling('src/2fa/handler.ts')).toBe('src/2fa/handler.ts');
+  });
+
+  it('maps Lua colon-method spelling onto the qualified form', () => {
+    expect(normalizeQuerySpelling('logger:log message')).toBe('logger.log message');
+  });
+});