[FEATURE] Add guida upgrade command

[decioferreira]

This fixes #138.

This PR adds a new guida upgrade command to safely upgrade project dependencies without manual editing of guida.json or elm.json.

The command:

• Reads guida.json or elm.json
• Upgrades direct dependencies to the newest compatible versions (safe mode, same major)
• Includes direct test-dependencies in the upgrade plan
• Updates application versions and package constraints deterministically
• Verifies the resulting project and rolls back on verification failure
• Reports planned dependency changes and clear errors when no valid upgrade is possible