Add droplet size descriptions and filtering across interactive commands

[fcasal]

• Add a Type column from DigitalOcean's own description field, so tier names come from the API and are described vs only a slug name such as so-2vcpu-16gb-intel
• Implemented a filter: cpu>=8 mem>=32 price<=300.
• Prompts get readline line editing and up-arrow history.

The following image shows the result of running ? mem >= 16 price <= 200, together with the accompanying machine descriptions

[ret2libc]

Please use one consistent default unit for memory filters—GB would work—and document it in the prompt help. Currently, mem>=1023 means 1023 GB, while mem>=1024 means 1 GB. Explicit mb/gb/tb suffixes can remain supported.

Filtering should be available wherever users select a droplet size, including interactive creation, initialization, and both resize paths. The shared helper appears to cover these already; please add command-level tests for interactive creation and resizing to verify that integration, and broaden the PR title to reflect the scope.

[ret2libc]

Reviewed the current head. The size filtering behavior and command integrations are covered; 384 tests pass with color enabled. The ANSI assertion in one test fails only under this workspace’s NO_COLOR=1 setting.