fix(lapack): add missing string module dependencies (#1063)

The lapack library includes stdlib_io.fypp which uses the string_type
constructor. This constructor is implemented in the submodule
stdlib_string_type_constructor, which in turn depends on stdlib_strings
and its submodule stdlib_strings_to_string.

Without these files, linking fails on some platforms (e.g., PowerPC macOS)
with undefined symbol errors for __stdlib_string_type_MOD_new_string.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

Author: perazz

src/lapack/CMakeLists.txt

@@ -7,6 +7,9 @@ set(lapack_fppFiles
     ../stdlib_io.fypp
     ../stdlib_ascii.fypp
     ../stdlib_string_type.fypp
+    ../stdlib_string_type_constructor.fypp
+    ../stdlib_strings.fypp
+    ../stdlib_strings_to_string.fypp
     stdlib_lapack_base.fypp
     stdlib_lapack_solve.fypp
     stdlib_lapack_others.fypp