feat(WP-0016): build infrastructure — ghcid standalone script and error-fix loop workplan

- scripts/compile-check: runs ghcid in isolation (no postgres/tailwind) for fast
  incremental compilation feedback; writes errors to /tmp/ihub-compile-errors.txt
- .ghci: add -fkeep-going so GHC reports all module errors in one pass
- WP-0016 workplan: documents module dependency layers, error-fix SOP,
  and autonomous ralph-loop approach for iterative error fixing

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

scripts/compile-check

@@ -0,0 +1,44 @@
+#!/usr/bin/env bash
+# bin/compile-check — run ghcid standalone for fast compilation feedback.
+#
+# Does NOT start postgres or tailwind — just GHC.
+# Relies on .ghci (sets -j1, loads IHP config).
+#
+# Usage:
+#   bin/compile-check            # interactive: errors shown in terminal + log
+#   bin/compile-check --bg       # log only (for Claude monitoring loop)
+#
+# Pre-requisite: run inside `devenv shell` (IHP_LIB must be set).
+# Or: `devenv shell -- bin/compile-check`
+#
+# Log file: /tmp/ihub-compile-errors.txt (override with IHUB_COMPILE_LOG)
+
+set -euo pipefail
+
+LOGFILE="${IHUB_COMPILE_LOG:-/tmp/ihub-compile-errors.txt}"
+MODE="${1:-}"
+
+# Ensure IHP_LIB is available
+if [[ -z "${IHP_LIB:-}" ]]; then
+    echo "ERROR: IHP_LIB is not set. Run inside devenv shell:" >&2
+    echo "  devenv shell -- bin/compile-check" >&2
+    exit 1
+fi
+
+: > "$LOGFILE"
+echo "[compile-check] Log: $LOGFILE"
+echo "[compile-check] Mode: ${MODE:-interactive}"
+
+if [[ "$MODE" == "--bg" ]]; then
+    # Background: write to log only, no colour/title
+    exec ghcid \
+        --no-title \
+        --outputfile "$LOGFILE" \
+        --command "ghci"
+else
+    # Interactive: show errors in terminal AND write to log
+    exec ghcid \
+        --no-title \
+        --outputfile "$LOGFILE" \
+        --command "ghci"
+fi