add nix flake devshell and process-compose

mirrors youngstartup setup. flake provides php 8.4, composer,
nodejs, postgresql, cypress, typescript, process-compose. shellHook
seeds a per-repo postgres cluster at .postgres/. process-compose
orchestrates postgres + backend (laravel) + vite (vue spa) for
local dev. .envrc auto-loads the flake via direnv. mailpit and
gitlab-ci-local omitted - not needed for tide blogging app.

.envrc

@@ -0,0 +1,10 @@
+# Load the flake environment
+use flake
+
+# Use PHP and Node layouts
+layout php
+layout node
+
+# Watch for dependency changes
+watch_file composer.json
+watch_file package.json

.gitignore

@@ -0,0 +1,9 @@
+# Nix devshell artefacts
+/.postgres/
+/.direnv/
+result
+result-*
+
+# Process-compose state
+/.pc.*
+process-compose-*.log

flake.lock

@@ -0,0 +1,61 @@
+{
+  "nodes": {
+    "nixpkgs": {
+      "locked": {
+        "lastModified": 1777954456,
+        "narHash": "sha256-hGdgeU2Nk87RAuZyYjyDjFL6LK7dAZN5RE9+hrDTkDU=",
+        "owner": "NixOs",
+        "repo": "nixpkgs",
+        "rev": "549bd84d6279f9852cae6225e372cc67fb91a4c1",
+        "type": "github"
+      },
+      "original": {
+        "owner": "NixOs",
+        "ref": "nixos-unstable",
+        "repo": "nixpkgs",
+        "type": "github"
+      }
+    },
+    "root": {
+      "inputs": {
+        "nixpkgs": "nixpkgs",
+        "utils": "utils"
+      }
+    },
+    "systems": {
+      "locked": {
+        "lastModified": 1681028828,
+        "narHash": "sha256-Vy1rq5AaRuLzOxct8nz4T6wlgyUR7zLU309k9mBC768=",
+        "owner": "nix-systems",
+        "repo": "default",
+        "rev": "da67096a3b9bf56a91d16901293e51ba5b49a27e",
+        "type": "github"
+      },
+      "original": {
+        "owner": "nix-systems",
+        "repo": "default",
+        "type": "github"
+      }
+    },
+    "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"
+      }
+    }
+  },
+  "root": "root",
+  "version": 7
+}

flake.nix

@@ -0,0 +1,48 @@
+{
+  inputs = {
+    nixpkgs.url = "github:NixOs/nixpkgs/nixos-unstable";
+    utils.url = "github:numtide/flake-utils";
+  };
+  outputs = { self, nixpkgs, utils }:
+    utils.lib.eachDefaultSystem (system:
+      let
+        pkgs = nixpkgs.legacyPackages.${system};
+      in {
+        devShells.default = pkgs.mkShell {
+          buildInputs = with pkgs; [
+            onefetch
+            php
+            phpPackages.composer
+            phpPackages.php-codesniffer
+            vscode-langservers-extracted
+            sqlite
+            nodejs
+            nixfmt-rfc-style
+            nixfmt-tree
+            cypress
+            yaml-language-server
+            typescript
+            postgresql
+            process-compose
+          ];
+
+          shellHook = ''
+            export PGDATA="$PWD/.postgres"
+            export PGHOST="$PGDATA"
+            export PGUSER="postgres"
+            export PGDATABASE="postgres"
+
+            if [ ! -d "$PGDATA" ]; then
+              echo "[pg] initializing cluster at $PGDATA"
+              initdb --auth=trust --username=postgres --no-locale --encoding=UTF8 >/dev/null
+              {
+                echo "listen_addresses = '127.0.0.1'"
+                echo "unix_socket_directories = '$PGDATA'"
+              } >> "$PGDATA/postgresql.conf"
+            fi
+
+            echo "[dev] run 'process-compose up' to start postgres + backend + vite"
+          '';
+        };
+      });
+}

process-compose.yaml

@@ -0,0 +1,37 @@
+version: "0.5"
+
+processes:
+  postgres:
+    command: postgres -D "$PGDATA" -k "$PGDATA" -c listen_addresses=127.0.0.1
+    shutdown:
+      signal: 2
+    readiness_probe:
+      exec:
+        command: pg_isready -h "$PGDATA"
+      initial_delay_seconds: 1
+      period_seconds: 2
+
+  backend:
+    command: php artisan serve --host=127.0.0.1 --port=8000
+    working_dir: ./backend
+    depends_on:
+      postgres:
+        condition: process_healthy
+    readiness_probe:
+      http_get:
+        host: 127.0.0.1
+        port: 8000
+        path: /up
+      initial_delay_seconds: 2
+      period_seconds: 10
+
+  vite:
+    command: npm run dev
+    working_dir: ./frontend/blog_portal
+    readiness_probe:
+      http_get:
+        host: 127.0.0.1
+        port: 5173
+        path: /
+      initial_delay_seconds: 2
+      period_seconds: 2