Add dependecies.go to install packages

[archandatta]

This PR adds methods to install dependencies after copying templates into a new directory.

Testing

• run make build && ./bin/kernel create
• select name, language, template
• cd into directory and check if node_modules or .venv exist

---

Note

Adds language-specific dependency installation to the create flow with tool availability checks, fallback messaging, and comprehensive tests.

• CLI Create Flow (cmd/create.go):
  • Invoke create.InstallDependencies after copying templates; minor output tweak with pterm.Printfln.
• Dependency Setup (pkg/create/dependencies.go):
  • Install deps per language via InstallCommands with spinner.
  • Handle missing required tools using RequiredTools and print installation/next steps.
  • Gracefully handle install failures with warnings and manual steps.
• Types and Config (pkg/create/types.go):
  • Add RequiredTools, InstallCommands, and Tools.CheckToolAvailable.
• Tests (cmd/create_test.go):
  • Add tests for all templates with/without dependency installation.
  • Cover failure scenarios (install command fails) and missing required tools.
  • Validate created files, environment artifacts (node_modules, .venv), and next-step output.

^{Written by Cursor Bugbot for commit 66d4e7b. This will update automatically on new commits. Configure here.}

[cursor]

Bug: Python deploy instruction references wrong entry file

The getNextStepsWithToolInstall function for Python tells users to run kernel deploy index.py, but Python templates use main.py as the entry point (as confirmed by both the test assertions and the actual template files in pkg/templates/python/). Users following these instructions will attempt to deploy a non-existent file.