Fix two critical bugs in the argument parsing logic that caused incorrect
behavior when --short-name parameter was used:
1. **Index offset bug**: The loop started at i=0 and used i < $#, which
incorrectly processed $0 (script name) as the first argument and
skipped the last actual parameter. Changed to i=1 and i <= $# to
properly iterate through actual command-line arguments ($1 to $#).
2. **Boundary condition bug**: The condition `[ $((i + 1)) -ge $# ]`
incorrectly flagged valid arguments as missing. When --short-name was
at position $#-1, the next position $# was valid but treated as
out-of-bounds. Changed to `[ $((i + 1)) -gt $# ]` for correct validation.
3. **Enhanced validation**: Added check to ensure --short-name value is
not another option (doesn't start with --).
**Before**:
- `script --json "desc" --short-name "test"` → Error: requires a value
- `script --json "desc1" "desc2" --short-name` → Generated wrong branch name
**After**:
- `script --json "desc" --short-name "test"` → Works correctly
- `script --json "desc1" "desc2" --short-name` → Proper error message
This ensures the script correctly supports both parameter orders:
- `[--json] [--short-name <name>] <feature_description>`
- `[--json] <feature_description> [--short-name <name>]`
