Path completion now works for:
- ./<TAB> - current directory
- ../<TAB> - parent directory
- ~/<TAB> - home directory
- /<TAB> (not at start of line) - root directory
Command completion (/<TAB>) only triggers at the start of the line.
If no command matches, falls through to path completion (e.g., /etc).
Quote-aware word extraction handles paths with spaces:
- "~/My Files/<TAB>" works correctly
Added tests for:
- Path prefix detection
- Word extraction with quotes
- Command vs path disambiguation
96cc18b83c