fix: exclude shim file from bundled dependency detection

When shims: true is enabled, tsdown injects ESM shims (__filename,
__dirname) by importing from its own esm-shims.js. Since this file
resides in node_modules/tsdown/, the dependency detection in
generateBundle incorrectly flags tsdown itself as a bundled dependency
and shows a confusing hint suggesting the user configure deps.onlyBundle.

Skip the shimFile when iterating module IDs in the generateBundle
handler so the shim import is not reported as a bundled dependency.

Closes #907

Author: sxzz

src/features/deps.ts

@@ -218,6 +218,7 @@ export function DepsPlugin(
           if (chunk.type === 'asset') continue
 
           for (const id of chunk.moduleIds) {
+            if (id === shimFile) continue
             const parsed = await readBundledDepInfo(id)
             if (!parsed) continue