docs: add project README, reference docs, license, CLA, and contributing guide

Apache-2.0 license with CLA for dual-licensing. Lefthook enforces
Signed-off-by on all commits. AGENTS.md updated with new modules.

Signed-off-by: Sienna Meridian Satterwhite <sienna@r3t.io>
Signed-off-by: Sienna Meridian Satterwhite <sienna@sunbeam.pt>

lefthook.yml

@@ -0,0 +1,29 @@
+# Lefthook configuration for Sunbeam Proxy
+# Install: lefthook install
+
+commit-msg:
+  commands:
+    dco-signoff:
+      run: |
+        if ! grep -q "^Signed-off-by: " "{1}"; then
+          echo ""
+          echo "ERROR: Missing Signed-off-by line."
+          echo ""
+          echo "All commits to Sunbeam Proxy must include a Signed-off-by line"
+          echo "indicating agreement with the Contributor License Agreement (CLA.md)."
+          echo ""
+          echo "Use: git commit -s"
+          echo "  or: git commit --signoff"
+          echo ""
+          exit 1
+        fi
+
+pre-commit:
+  parallel: true
+  commands:
+    cargo-check:
+      glob: "*.rs"
+      run: cargo check --quiet
+    cargo-fmt:
+      glob: "*.rs"
+      run: cargo fmt -- --check