clang-tidy: sync argument names in prototype and definition

Discovered with clang-tidy checker
`readability-inconsistent-declaration-parameter-name`.

Also:
- do not enforce the above because of inconsistencies still present
  between public API prototypes and definitions. (Also betwen man page
  protos, and man page examples, and other parts of the code, e.g.
  `easy` vs `curl` vs `d` vs `handle`) Perhaps subject for a future
  effort:
  https://github.com/curl/curl/actions/runs/22166472728/job/64094691653
- enable and fix `readability-named-parameter` where missing.

Refs:
https://clang.llvm.org/extra/clang-tidy/checks/readability/inconsistent-declaration-parameter-name.html
https://clang.llvm.org/extra/clang-tidy/checks/readability/named-parameter.html

Closes #20624

src/tool_paramhlp.h

@@ -44,7 +44,7 @@ ParameterError str2unum(long *val, const char *str);
 ParameterError oct2nummax(long *val, const char *str, long max);
 ParameterError str2unummax(long *val, const char *str, long max);
 ParameterError secs2ms(long *val, const char *str);
-ParameterError proto2num(const char * const *val, char **obuf,
+ParameterError proto2num(const char * const *val, char **ostr,
                          const char *str);
 ParameterError check_protocol(const char *str);
 ParameterError str2offset(curl_off_t *val, const char *str);