runtime(cangjie): Fixes and improvements for syntax script

runtime(cangjie): Fixes and improvements for syntax script

Housekeeping:
- Add GitHub repository link
- Update Last Change date

Style:
- Add Vim modeline for consistent formatting
- Unify indentation style (spaces to tabs)
- Wrap long cluster definitions for readability

New Features:
- Add highlighting for escape sequences
- Add error highlighting for invalid rune literals
- Add syntax-based folding support

Fixes:
- Fix rune matching to allow only a single character/escape
- Fix highlighting for double-quoted rune literals
- Fix highlighting for floats with exponents and type suffixes

Co-authored-by: dkearns <dougkearns@gmail.com>
Signed-off-by: Wu Junkai <wujunkai20041123@outlook.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>