docs: add Language Support section to smart-explore/SKILL.md (#1651)

tree-sitter language docs belonged in smart-explore but were absent;
this adds the Bundled Languages table (10 languages) with correct placement.

Generated by Claude Code
Vibe coded by ousamabenyounes

Co-Authored-By: Claude <noreply@anthropic.com>

tests/utils/skill-docs-placement.test.ts

@@ -0,0 +1,43 @@
+/**
+ * Regression test for misplaced smart-explore language docs (#1651)
+ *
+ * The smart-explore language support section was missing from smart-explore/SKILL.md
+ * and had previously been in mem-search/SKILL.md (where it doesn't belong).
+ */
+import { describe, it, expect } from 'bun:test';
+import { existsSync, readFileSync } from 'fs';
+import { join } from 'path';
+
+const SKILLS_DIR = join(import.meta.dir, '../../plugin/skills');
+
+describe('skill docs placement (#1651)', () => {
+  it('smart-explore/SKILL.md contains Language Support section', () => {
+    const path = join(SKILLS_DIR, 'smart-explore/SKILL.md');
+    expect(existsSync(path)).toBe(true);
+    const content = readFileSync(path, 'utf-8');
+
+    expect(content).toContain('Language Support');
+    expect(content).toContain('tree-sitter');
+  });
+
+  it('smart-explore/SKILL.md lists bundled languages', () => {
+    const content = readFileSync(join(SKILLS_DIR, 'smart-explore/SKILL.md'), 'utf-8');
+
+    // Core languages must be documented
+    expect(content).toContain('JavaScript');
+    expect(content).toContain('TypeScript');
+    expect(content).toContain('Python');
+    expect(content).toContain('Go');
+    expect(content).toContain('Rust');
+  });
+
+  it('mem-search/SKILL.md does NOT contain tree-sitter or language grammar docs', () => {
+    const path = join(SKILLS_DIR, 'mem-search/SKILL.md');
+    expect(existsSync(path)).toBe(true);
+    const content = readFileSync(path, 'utf-8');
+
+    // Language support docs belong in smart-explore, not mem-search
+    expect(content).not.toContain('tree-sitter');
+    expect(content).not.toContain('Bundled Languages');
+  });
+});