create-a-container: add a /containers/:id/edit route

[runleveldev]

Issue: Add /containers/<id>/edit route for updating container configurations

Description:
There is currently no route to edit or update existing container configurations. This limits management capabilities to creation only.

Recommendation:
Implement a new route:

GET  /containers/:id/edit   →  render edit form  
PUT  /containers/:id        →  process updates  

Benefits:

• Enables users to modify container settings after creation
• Aligns with RESTful routing conventions
• Improves usability and management flexibility

[runleveldev]

Added in #136