fix: handle user abort (Ctrl+C) gracefully

[JannikSt]

Summary

• Catch typer.Abort exceptions to show a clean "Operation cancelled" message instead of ugly tracebacks when users press Ctrl+C during interactive prompts
• Added global handler in main.py for CLI-wide coverage
• Added specific handlers in pods.py for create and connect commands (which have their own exception handling blocks)

Before

Select GPU type number [1]: ^C
Unexpected error: 
Traceback (most recent call last):
  File ".../pods.py", line 476, in create
    gpu_type_idx = typer.prompt("Select GPU type number", type=int, default=1)
  ...
click.exceptions.Abort

After

Select GPU type number [1]: ^C
Operation cancelled

Test plan

• Run prime pods create, press Ctrl+C during prompt - should show clean message
• Verify exit code is 0 (clean exit) instead of 1 (error)
• Existing tests pass

Fixes #34

---

Note

Catch typer.Abort to show a clean "Operation cancelled" message and exit 0 in the CLI entrypoint and pods create/connect commands.

• CLI:
  • Add global typer.Abort handler in prime_cli/main.py:run() to print "Operation cancelled" and exit 0.
• Pods Commands (prime_cli/commands/pods.py):
  • create: Catch typer.Abort, print "Operation cancelled", exit 0.
  • connect (aka ssh): Catch typer.Abort, print "Operation cancelled", exit 0.

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