feat(cli): add wmk hub command

[DingmaomaoBJTU]

Summary

• Adds wmk hub CLI command backed by hub_models.json (17 validated models)
• wmk hub renders a 3-column catalog table (Model / Task / Model Type) in a blue Panel with a hint line printed below the border
• wmk hub --model-type <type> / --task <task> case-insensitive filters
• wmk hub --model <id> renders 3 separate Panels: General Info, Latency (ms), and Accuracy
• --output <file> saves results as JSON; no default auto-save without --output
• Partial and case-insensitive model ID matching; ambiguous match → non-zero exit with suggestions
• ASCII-only icons ([+] [~] [!]); no UTF-8 emoji
• 28 unit tests in tests/unit/commands/test_hub.py via click.testing.CliRunner

Closes #117