feat(importmap): implement package-scoped vendor structure for staticDeps

[tatang26]

Summary

This PR changes the way vendor packages are downloaded and organized in the importmap tool.

Currently the importmap tool downloads packages into a flattened structure. This approach is not including the download of packages that require internal dependencies (scopes).

The new approach downloads all package scopes and places them within their vendored path, creating an isolated directory structure per package:

// Before
vendor/
└── package@1.0.0.js              # Single flat file
// After  
vendor/
└── package@1.0.0/
    ├── dist/index.js             # Main entry point
    ├── _/helper.js               # Internal dependencies
    └── scopes/                   # Isolated scoped dependencies
        └── dependency@2.0.0/

Breaking Change

After upgrading, you must run:

go run github.com/leapkit/leapkit/tools/importmap@latest pristine

This reorganizes the vendor directory to the new structure.

⚠️ Important: Embed Directive Update

Some internal dependencies are placed in _/ folders (e.g., _/index.js). The Go embed directive with standard * pattern excludes directories starting with _ or .

Update required in template/internal/system/assets/assets.go:

// Before:
//go:embed *

// After:
//go:embed all:*

Without this change, _/ directories won't be embedded and the application will fail at runtime.
See Go embed docs for details.