feat(WP-0016/C1-C4): Layer 2 isolation and clean-base infrastructure

- Add Web/Controller/Prelude.hs (was missing; 8 controllers failed to import it)
- Add .ghci-core and scripts/compile-check-core to compile Layer 1+2 in
  isolation without loading Main.hs or any controller/view (Layer 3)
- Fix Application/Helper/BottleneckDetector.hs: replace coerce :: Id' -> UUID
  with unpackId (IHP Id' wraps a type family; Data.Coerce cannot cross it)
- Fix devenv.nix: add pkgs.nodePackages.tailwindcss so devenv process scripts
  find the tailwindcss binary (devenv v2 builds scripts with only local packages)

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

.ghci-core

@@ -0,0 +1,84 @@
+-- .ghci-core — loads ONLY Layer 1 (Generated.Types, Web.Types) and Layer 2
+-- (Application/Helper/*) for independent compilation verification.
+--
+-- Usage (inside devenv shell):
+--   ghci -ghci-script .ghci-core
+-- or:
+--   ghcid --command "ghci -ghci-script .ghci-core"
+--
+-- This file intentionally does NOT load Main.hs or any Web/Controller / Web/View
+-- modules. Once this reaches "Ok, N modules loaded" with no errors, the core
+-- layer is verified clean and Layer 3 errors are isolated to controllers/views.
+
+-- NOTE: we do NOT use :loadFromIHP applicationGhciConfig here because it ends
+-- with ":l Main.hs" which would load all of Layer 3.  Instead we duplicate
+-- the environment flags from applicationGhciConfig and load only core modules.
+:set -i.
+:set -iIHP/ihp-hsx
+:set -iConfig
+:set -ibuild
+:set -iIHP
+:set -XOverloadedStrings
+:set -XNoImplicitPrelude
+:set -XImplicitParams
+:set -XRank2Types
+:set -XDisambiguateRecordFields
+:set -XNamedFieldPuns
+:set -XDuplicateRecordFields
+:set -XOverloadedLabels
+:set -XFlexibleContexts
+:set -XTypeSynonymInstances
+:set -XFlexibleInstances
+:set -XQuasiQuotes
+:set -XTypeFamilies
+:set -XPackageImports
+:set -XScopedTypeVariables
+:set -XRecordWildCards
+:set -XTypeApplications
+:set -XDataKinds
+:set -XInstanceSigs
+:set -XDeriveGeneric
+:set -XMultiParamTypeClasses
+:set -XTypeOperators
+:set -XUndecidableInstances
+:set -Wno-unsafe -Wno-name-shadowing -Wno-monomorphism-restriction -Wno-safe -Wno-missing-local-signatures -Wno-missing-home-modules
+:set -XDeriveDataTypeable
+:set -XLambdaCase
+:set -XDefaultSignatures
+:set -XEmptyDataDeriving
+:set -XBangPatterns
+:set -XBlockArguments
+:set -XMultiWayIf
+:set -XFunctionalDependencies
+:set -package ihp
+:set -fbyte-code
+:set -j1
+:set -fkeep-going
+:set -Wno-partial-type-signatures
+:set -XPartialTypeSignatures
+:set -XStandaloneDeriving
+:set -XDerivingVia
+:set -XTemplateHaskell
+:set -XDeepSubsumption
+:set -XOverloadedRecordDot
+:set -Werror=missing-fields
+:set -fwarn-incomplete-patterns
+:set -package ghc
+:set -fno-warn-ambiguous-fields
+
+-- Layer 1: generated types and Web.Types
+:load build/Generated/Types.hs Web/Types.hs Web/Routes.hs
+
+-- Layer 2: helpers (order matters — imports within Layer 2 must be satisfied)
+:add Application/Helper/View.hs
+:add Application/Helper/Controller.hs
+:add Application/Helper/TypeRegistry.hs
+:add Application/Helper/ModelRouter.hs
+:add Application/Helper/RoutingEngine.hs
+:add Application/Helper/FrictionScore.hs
+:add Application/Helper/BottleneckDetector.hs
+:add Application/Helper/HubHealth.hs
+:add Application/Helper/CorrelationEngine.hs
+:add Application/Helper/CrossHubPropagation.hs
+:add Application/Helper/AgentBridge.hs
+:add Application/Helper/ApiRateLimit.hs