feat: rename the repo from schema to lib

[TheOutdoorProgrammer]

Summary

Renames the repository from gremllm/schema to gremllm/lib to better reflect its purpose as a general-purpose library for LLM-optimized content serving.

Motivation

The name schema was too specific and didn't accurately represent the library's broader functionality. lib is more appropriate for a general-purpose middleware library that can be used across different contexts.

Changes

• Updated Go module path from github.com/gremllm/schema to github.com/gremllm/lib
• Updated all import statements across the codebase to use the new module path
• Updated GitHub badges and links in README.md to point to the new repository
• Updated goreleaser configuration to reference the new repository name
• Updated project structure diagrams in documentation
• Cleaned up unused golang.org/x/text dependency from go.sum

Breaking Changes

⚠️ This is a breaking change for existing users. Anyone importing this library will need to update their import paths from github.com/gremllm/schema to github.com/gremllm/lib.

Migration Guide

Update all imports in your code:

- import "github.com/gremllm/schema/internal/middleware"
+ import "github.com/gremllm/lib/internal/middleware"

Then run:

go mod tidy