feat(jfrog): add pnpm package manager support

[Edd88-pixel]

Why

The JFrog token and OAuth modules can configure several package managers, but pnpm is not currently supported. Adding pnpm configuration lets workspaces resolve pnpm packages through Artifactory while preserving the existing npm configuration contract.

Closes #1074.

Changes

• Add an optional package_managers.pnpm repository list to both JFrog modules.
• Configure pnpm with jf pnpmc --global --repo-resolve and generate the shared npm/pnpm .npmrc content.
• Validate that npm and pnpm use the same repository list when both are enabled because they share ~/.npmrc.
• Add Terraform and Bun coverage for pnpm configuration and mismatched repositories.
• Document pnpm requirements and usage, and bump both module examples to version 1.3.0.

Validation

• bun test main.test.ts in jfrog-token: 12 tests passed, 35 assertions.
• terraform test -verbose in jfrog-oauth: 14 tests passed.
• terraform validate in both modules: passed.
• Terraform formatting and Prettier checks: passed.

Type of Change

• New module
• New template
• Bug fix
• Feature/enhancement
• Documentation
• Other

Module Information

Paths: registry/coder/modules/jfrog-token, registry/coder/modules/jfrog-oauth
New version: v1.3.0
Breaking change: [ ] Yes [x] No

Testing & Validation

• Tests pass (bun test)
• Code formatted (bun fmt)
• Changes tested locally

Related Issues

Closes #1074.