refactor: consolidate status command into profile command

Problem

The status command did not display user activity stats and profile would be a more appropriate name for the command.

Solution

• Renamed status command to profile
• Added --quiet/-q flag to profile for basic login status check
• Full profile mode now fetches fresh data from API and shows activity stats
• Extracted _show_user_table() and _show_stats_table() helper functions
• Added fetch_user_stats() API helper for fetching contribution stats

Usage

• corpus-client profile -q — Quick status check (login state, API URL, cached user details)
• corpus-client profile — Full profile with fresh API data and activity stats

Files Changed

• src/corpus_client_cli/cli.py — Removed status, enhanced profile, added helpers
• tests/test_cli_commands.py — Updated tests for consolidated command

Closes #4 (closed)