feat: add notesmd-cli package and flake checks

- Add notesmd-cli package for Obsidian CLI interaction
- Add flake checks for package build verification
- Add documentation for notesmd-cli, sidecar, and td
- Update AGENTS.md to reference td instead of beads
- Format pkgs/default.nix with proper braces

pkgs/notesmd-cli/default.nix

@@ -0,0 +1,31 @@
+{
+  lib,
+  buildGoModule,
+  fetchFromGitHub,
+  nix-update-script,
+}:
+buildGoModule (finalAttrs: {
+  pname = "notesmd-cli";
+  version = "0.3.0";
+
+  src = fetchFromGitHub {
+    owner = "Yakitrak";
+    repo = "notesmd-cli";
+    tag = "v${finalAttrs.version}";
+    hash = "sha256-KJRaJ9Fw7oh108ljKw1Eb2r7hZXlFWC2NOrjhliuzVQ=";
+  };
+
+  vendorHash = null;
+
+  ldflags = ["-s" "-w"];
+
+  passthru.updateScript = nix-update-script {};
+
+  meta = {
+    description = "Obsidian CLI (Community) - Interact with Obsidian in the terminal";
+    homepage = "https://github.com/Yakitrak/notesmd-cli";
+    license = lib.licenses.mit;
+    platforms = lib.platforms.unix;
+    mainProgram = "notesmd-cli";
+  };
+})