feat: minimal IHP scaffold — T01-T05, T08 of IRP-WP-0001

- flake.nix adapted from inter-hub: appName=ihp-railiance-probe, stripped to
  core packages, GHC 9.10.3 Bug 1+2 overlays carried verbatim (pname check
  updated to ihp-railiance-probe-models)
- IHP project scaffold: Main.hs, Config.hs, App.cabal, Setup.hs, Makefile
- Schema: probes table (id, name, created_at)
- Health endpoint: GET /healthz → "ok" (HealthController)
- Probes CRUD: ProbesController + 4 views (Index, New, Show, Edit)
- Hspec test suite: Test/ProbeControllerSpec covers /probes and /healthz
- Helm chart in chart/: deployment, service, ingress, secret templates
- devenv.nix, devenv.yaml, .ghci, tailwind config

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

devenv.nix

@@ -0,0 +1,24 @@
+{ pkgs, lib, config, inputs, ... }:
+{
+  env.GHCRTS = "-A32m -M2g";
+
+  env.IHP_LIB = "${inputs.ihp.packages.${pkgs.stdenv.system}.ihp-env-var-backwards-compat}";
+  env.IHP     = "${inputs.ihp.packages.${pkgs.stdenv.system}.ihp-env-var-backwards-compat}";
+
+  languages.haskell.enable = true;
+  languages.haskell.package = pkgs.ghc.ghc.withPackages (p: with p; [
+    p.ihp
+    cabal-install
+    hlint
+    hspec
+    p.ihp-hspec
+  ]);
+  languages.haskell.lsp.enable = false;
+
+  packages = [
+    pkgs.ghc.ghcid
+    pkgs.nodePackages.tailwindcss
+  ];
+
+  processes.tailwind.exec = "tailwindcss -c tailwind/tailwind.config.js -i ./tailwind/app.css -o static/app.css --watch=always";
+}