fix(doctor): improve AST-Grep NAPI detection for bunx environments

Use dynamic import instead of require.resolve() to detect @ast-grep/napi
installation. This fixes false negatives when running via bunx where the
module exists in ~/.config/opencode/node_modules but isn't resolvable
from the temporary execution directory.

Also adds fallback path checks for common installation locations.

Fixes #898

src/cli/doctor/checks/dependencies.test.ts

@@ -16,10 +16,10 @@ describe("dependencies check", () => {
   })
 
   describe("checkAstGrepNapi", () => {
-    it("returns dependency info", () => {
+    it("returns dependency info", async () => {
       // #given
       // #when checking ast-grep napi
-      const info = deps.checkAstGrepNapi()
+      const info = await deps.checkAstGrepNapi()
 
       // #then should return valid info
       expect(info.name).toBe("AST-Grep NAPI")
@@ -95,7 +95,7 @@ describe("dependencies check", () => {
 
     it("returns pass when installed", async () => {
       // #given napi installed
-      checkSpy = spyOn(deps, "checkAstGrepNapi").mockReturnValue({
+      checkSpy = spyOn(deps, "checkAstGrepNapi").mockResolvedValue({
         name: "AST-Grep NAPI",
         required: false,
         installed: true,

src/cli/doctor/checks/dependencies.ts

@@ -56,9 +56,10 @@ export async function checkAstGrepCli(): Promise<DependencyInfo> {
   }
 }
 
-export function checkAstGrepNapi(): DependencyInfo {
+export async function checkAstGrepNapi(): Promise<DependencyInfo> {
+  // Try dynamic import first (works in bunx temporary environments)
   try {
-    require.resolve("@ast-grep/napi")
+    await import("@ast-grep/napi")
     return {
       name: "AST-Grep NAPI",
       required: false,
@@ -67,6 +68,28 @@ export function checkAstGrepNapi(): DependencyInfo {
       path: null,
     }
   } catch {
+    // Fallback: check common installation paths
+    const { existsSync } = await import("fs")
+    const { join } = await import("path")
+    const { homedir } = await import("os")
+
+    const pathsToCheck = [
+      join(homedir(), ".config", "opencode", "node_modules", "@ast-grep", "napi"),
+      join(process.cwd(), "node_modules", "@ast-grep", "napi"),
+    ]
+
+    for (const napiPath of pathsToCheck) {
+      if (existsSync(napiPath)) {
+        return {
+          name: "AST-Grep NAPI",
+          required: false,
+          installed: true,
+          version: null,
+          path: napiPath,
+        }
+      }
+    }
+
     return {
       name: "AST-Grep NAPI",
       required: false,
@@ -127,7 +150,7 @@ export async function checkDependencyAstGrepCli(): Promise<CheckResult> {
 }
 
 export async function checkDependencyAstGrepNapi(): Promise<CheckResult> {
-  const info = checkAstGrepNapi()
+  const info = await checkAstGrepNapi()
   return dependencyToCheckResult(info, CHECK_NAMES[CHECK_IDS.DEP_AST_GREP_NAPI])
 }