chore: add Nix flake dev shell (Python 3.12, Node 20, pnpm, PostgreSQL, Redis)

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

flake.lock

@@ -0,0 +1,61 @@
+{
+  "nodes": {
+    "flake-utils": {
+      "inputs": {
+        "systems": "systems"
+      },
+      "locked": {
+        "lastModified": 1731533236,
+        "narHash": "sha256-l0KFg5HjrsfsO/JpG+r7fRrqm12kzFHyUHqHCVpMMbI=",
+        "owner": "numtide",
+        "repo": "flake-utils",
+        "rev": "11707dc2f618dd54ca8739b309ec4fc024de578b",
+        "type": "github"
+      },
+      "original": {
+        "owner": "numtide",
+        "repo": "flake-utils",
+        "type": "github"
+      }
+    },
+    "nixpkgs": {
+      "locked": {
+        "lastModified": 1778003029,
+        "narHash": "sha256-q/nkKLDtHIyLjZpKhWk3cSK5IYsFqtMd6UtXF3ddjgA=",
+        "owner": "NixOS",
+        "repo": "nixpkgs",
+        "rev": "0c88e1f2bdb93d5999019e99cb0e61e1fe2af4c5",
+        "type": "github"
+      },
+      "original": {
+        "owner": "NixOS",
+        "ref": "nixos-25.11",
+        "repo": "nixpkgs",
+        "type": "github"
+      }
+    },
+    "root": {
+      "inputs": {
+        "flake-utils": "flake-utils",
+        "nixpkgs": "nixpkgs"
+      }
+    },
+    "systems": {
+      "locked": {
+        "lastModified": 1681028828,
+        "narHash": "sha256-Vy1rq5AaRuLzOxct8nz4T6wlgyUR7zLU309k9mBC768=",
+        "owner": "nix-systems",
+        "repo": "default",
+        "rev": "da67096a3b9bf56a91d16901293e51ba5b49a27e",
+        "type": "github"
+      },
+      "original": {
+        "owner": "nix-systems",
+        "repo": "default",
+        "type": "github"
+      }
+    }
+  },
+  "root": "root",
+  "version": 7
+}

flake.nix

@@ -0,0 +1,62 @@
+{
+  description = "CentralCloud OnCall — Grafana OnCall fork (Python/Django + Node.js/pnpm)";
+
+  inputs = {
+    nixpkgs.url = "github:NixOS/nixpkgs/nixos-25.11";
+    flake-utils.url = "github:numtide/flake-utils";
+  };
+
+  nixConfig = {
+    extra-substituters = [
+      "https://cache.centralcloud.com/default"
+    ];
+    extra-trusted-public-keys = [
+      "default:ywfU21WX06iOn2Ec2lae1jYh4w8LO4IQkmp06vJzsk8="
+    ];
+  };
+
+  outputs = {
+    nixpkgs,
+    flake-utils,
+    ...
+  }:
+    flake-utils.lib.eachDefaultSystem (system: let
+      pkgs = import nixpkgs {inherit system;};
+    in {
+      devShells.default = pkgs.mkShell {
+        packages = with pkgs; [
+          # Python engine
+          python312
+          python312Packages.pip
+          python312Packages.virtualenv
+          uv
+
+          # Frontend (grafana-plugin)
+          nodejs_20
+          nodePackages.pnpm
+
+          # Dev tooling
+          gnumake
+          git
+          jq
+          curl
+
+          # Local service dependencies (for running without docker)
+          postgresql_16
+          redis
+          rabbitmq-server
+        ];
+
+        shellHook = ''
+          echo "CentralCloud OnCall dev shell"
+          echo "  python : $(python --version)"
+          echo "  node   : $(node --version)"
+          echo "  pnpm   : $(pnpm --version)"
+          echo ""
+          echo "Engine:   cd engine && uv sync && source .venv/bin/activate"
+          echo "Frontend: cd grafana-plugin && pnpm install && pnpm dev"
+          echo "Compose:  docker compose up -d (db, redis, rabbitmq)"
+        '';
+      };
+    });
+}