Add omnixrc

This will be used in other projects down the line.

.envrc

@@ -1,3 +1,5 @@
+source ./omnixrc
+
 watch_file \
     nix/modules/nixpkgs.nix \
     nix/modules/rust.nix \
@@ -6,4 +8,8 @@ watch_file \
     *.nix \
     rust-toolchain.toml \
     crates/omnix-init/registry/flake.*
-use flake .
+
+# Dogfood our own ./omnixrc!
+# This may lead to compiling omnix if the commit hasn't yet been built in CI
+# But let's live with that for now.
+use omnix .

omnixrc

@@ -0,0 +1,10 @@
+# -*- mode: sh -*-
+# shellcheck shell=bash
+
+use_omnix() {
+  # TODO: Switch to nixpkgs version once we upstream
+  # Because, the user may not be a trusted-user leading to compilation!
+  nix --accept-flake-config run github:juspay/omnix health $*
+
+  use flake $*
+}