feat(T01): bootstrap IHP v1.5 project scaffold

Merged ihp-new generated scaffold into repo. Sets appName to inter-hub,
adds Nix flake with IHP inputs, devenv config, and standard IHP project
structure. Nix + ihp-new + direnv installed system-wide.

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

.envrc

@@ -0,0 +1,34 @@
+#!/usr/bin/env bash
+# See https://github.com/cachix/devenv/blob/main/templates/flake-parts/.envrc
+
+if ! has nix_direnv_version || ! nix_direnv_version 3.1.0; then
+    source_url "https://raw.githubusercontent.com/nix-community/nix-direnv/3.1.0/direnvrc" "sha256-yMJ2OVMzrFaDPn7q8nCBZFRYpL/f0RcHzhmw/i6btJM="
+fi
+
+export DEVENV_IN_DIRENV_SHELL=true
+
+watch_file flake.nix
+watch_file flake.lock
+
+mkdir -p "$PWD/.devenv"
+DEVENV_ROOT_FILE="$PWD/.devenv/root"
+printf %s "$PWD" >"$DEVENV_ROOT_FILE"
+if ! use flake . --override-input devenv-root "file+file://$DEVENV_ROOT_FILE" --accept-flake-config; then
+    echo "devenv could not be built. The devenv environment was not loaded. Make the necessary changes to devenv.nix and hit enter to try again." >&2
+fi
+
+# Include .env file if it exists locally. Use the .env file to load env vars that you don't want to commit to git
+if [ -f .env ]
+then
+    set -o allexport
+    source .env
+    set +o allexport
+fi
+# Add your env vars here
+#
+# E.g. export AWS_ACCESS_KEY_ID="XXXXX"
+
+# SMTP config for local development.
+export SMTP_HOST="127.0.0.1" # On some computers may need `127.0.1.1` instead.
+export SMTP_PORT="1025"
+export SMTP_ENCRYPTION="Unencrypted"