Add MCP server packages: annas, bitwarden, email, namecheap, navidrome, ovhcloud, slskd

Packages MCP servers currently used by Hermes that were not yet in this
repo. Real hashes computed via nix build on wilkes; nix flake check passes.

- annas-mcp: Go, buildGoModule (re-added, previously dropped as broken)
- bitwarden-mcp: npm @bitwarden/mcp-server
- mcp-email-server: Python, buildPythonApplication
- namecheap-mcp: npm namecheap-api-mcp
- navidrome-mcp: npm navidrome-mcp
- ovhcloud-mcp: npm from GitHub, tsc build step
- slskd-mcp: Python, fastmcp wrapper

packages/annas-mcp/package.nix

@@ -0,0 +1,36 @@
+{
+  lib,
+  buildGoModule,
+  fetchFromGitHub,
+  makeWrapper,
+}:
+
+buildGoModule rec {
+  pname = "annas-mcp";
+  version = "0.1.0-unstable-2026-06-26";
+
+  src = fetchFromGitHub {
+    owner = "iosifache";
+    repo = "annas-mcp";
+    rev = "c095963ad5d10d33da3c614495246b6ec7f680d4";
+    hash = "sha256-4gH5175yA9YYPVifXX3n9WCTRug0gOOfpQBLaGbvBcU=";
+  };
+
+  vendorHash = "sha256-2NdG5p2XfrhVgi388dRDBUSGwg6ybnzfn9495TWNGsA=";
+
+  nativeBuildInputs = [ makeWrapper ];
+
+  # The MCP server mode is invoked with "mcp" subcommand
+  postInstall = ''
+    wrapProgram $out/bin/annas-mcp \
+      --add-flags "mcp"
+  '';
+
+  meta = with lib; {
+    description = "MCP server and CLI tool for searching and downloading documents from Anna's Archive";
+    homepage = "https://github.com/iosifache/annas-mcp";
+    license = licenses.mit;
+    mainProgram = "annas-mcp";
+    platforms = platforms.linux;
+  };
+}