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>

Main.hs

@@ -0,0 +1,17 @@
+module Main where
+import IHP.Prelude
+
+import Config
+import qualified IHP.Server
+import IHP.RouterSupport
+import IHP.FrameworkConfig
+import IHP.Job.Types
+
+instance FrontController RootApplication where
+    controllers = []
+
+instance Worker RootApplication where
+    workers _ = []
+
+main :: IO ()
+main = IHP.Server.run config