refactor(ScriptHook): replace panics with error handling

- Replace all std.debug.panic() calls with proper error returns
- Add Error type with specific variants: GetModuleFileNameFailed,
  UnsupportedGame, DllLoadFailed, FunctionResolutionFailed, OutOfMemory
- Add GameVersionError for game type validation (NotGTAV, NotRDR2)
- Use std.once for thread-safe one-time initialization
- Update invoker.zig to propagate errors from ScriptHook functions

BREAKING CHANGE: All public functions now return errors instead of
panicking. Callers must use `try` or handle errors explicitly.

Author: playday3008