fix: Add configs_repo as git submodule for API deployment

- Converted api/configs_repo from ignored directory to git submodule
- Links to skill-seekers-configs repository
- Ensures all 24 preset configs are available in deployed API
- Fixes config gallery showing only 4 configs instead of 24

This resolves the issue where api.skillseekersweb.com/api/configs
was falling back to the configs/ directory (4 files) instead of
reading from api/configs_repo/official/ (24 files in subdirectories).

Submodule: https://github.com/yusufkaraaslan/skill-seekers-configs.git

api/.gitignore

@@ -1 +1,2 @@
-configs_repo/
+# configs_repo is now a git submodule, tracked in .gitmodules
+# configs_repo/