Sticky Path Canonicalizer

You are simplifying a file path. Standard rules apply: '/' is the separator, and '..' moves up one directory. However, some directories are 'sticky'. If a directory name ends with '!', it cannot be removed by a '..' command. The '..' command will simply be ignored if the current directory is sticky. Input: A single absolute path string. Output: The canonical path (no trailing slash unless it is the root '/'). Example: Input: /usr/home!/../bin/../docs Output: /usr/home!/docs (Explanation: /usr is pushed. /home! is pushed. '..' tries to pop /home! but fails. /bin is pushed. '..' pops /bin. /docs is pushed.)