feat(llm): add LLM integration instructions and handler

* Serve LLM instructions at `/llm`
* Include markdown content for memory instructions
* Update README with LLM integration details
* Add tests for LLM instructions handler
* Modify database migrations to use GUIDs for thoughts and projects

internal/app/llm.go

@@ -0,0 +1,22 @@
+package app
+
+import (
+	"net/http"
+
+	amcsllm "git.warky.dev/wdevs/amcs/llm"
+)
+
+func serveLLMInstructions(w http.ResponseWriter, r *http.Request) {
+	if r.URL.Path != "/llm" {
+		http.NotFound(w, r)
+		return
+	}
+
+	w.Header().Set("Content-Type", "text/markdown; charset=utf-8")
+	w.Header().Set("Cache-Control", "no-cache")
+	w.WriteHeader(http.StatusOK)
+	if r.Method == http.MethodHead {
+		return
+	}
+	_, _ = w.Write(amcsllm.MemoryInstructions)
+}