feat(bun): add GitHub URL support with # version separator

[eznix86]

Fixes #8264

What does this PR do?

Adds support for bun add github:username/repo#version syntax (useful for plugin)

How did you verify your code works?

Using tests

[github-actions]

Hey! Your PR title GitHub feat(bun): add GitHub URL support with # version separator doesn't follow conventional commit format.

Please update it to start with one of:

• feat: or feat(scope): new feature
• fix: or fix(scope): bug fix
• docs: or docs(scope): documentation changes
• chore: or chore(scope): maintenance tasks
• refactor: or refactor(scope): code refactoring
• test: or test(scope): adding or updating tests

Where scope is the package name (e.g., app, desktop, opencode).

See CONTRIBUTING.md for details.

[github-actions]

Thanks for your contribution!

This PR doesn't have a linked issue. All PRs must reference an existing issue.

Please:

1. Open an issue describing the bug/feature (if one doesn't exist)
2. Add Fixes #<number> or Closes #<number> to this PR description

See CONTRIBUTING.md for details.

[github-actions]

The following comment was made by an LLM, it may be inaccurate:

No duplicate PRs found

[rekram1-node]

This is interesting, can u update docs too to document it and link to Bun for reference so it's clear where the inspo is coming from (this may be an existing standard i just havent seen it b4)