feat(enforcement): Add pre-commit hook and CI verification for styled-components

Completes the 6-layer defense strategy for single styled-components instance:
- Add pre-commit hook blocking direct styled-components imports
- Add CI job verifying single styled-components version
- Configure git to use .githooks/pre-commit
- Update build job dependencies to include verification

Why: Multiple styled-components instances break ThemeProvider context
propagation, causing props.theme to be undefined. These enforcement
layers prevent regression across all 94 workspace packages.

Enforcement mechanisms now active:
1. ESLint (eslint.config.js) - lint-time blocking
2. Pre-commit hook (.githooks/pre-commit) - commit-time blocking
3. CI verification (.forgejo/workflows/ci.yml) - PR-time blocking
4. pnpm override (package.json) - install-time forcing
5. Documentation (docs/architecture/) - knowledge base
6. Wrapper package (@lilith/ui-styled-components) - single source

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

.forgejo/workflows/ci.yml

@@ -103,6 +103,51 @@ jobs:
         run: pnpm lint:imports:check
         continue-on-error: false
 
+  verify-styled-components:
+    name: Verify Single styled-components Version
+    runs-on: ubuntu-latest
+
+    steps:
+      - uses: actions/checkout@v4
+
+      - uses: pnpm/action-setup@v4
+
+      # Note: actions/setup-node@v4 skipped - incompatible with Forgejo act runner
+      - name: Configure Verdaccio NPM registry
+        run: |
+          echo "@lilith:registry=http://verdaccio:4873/" >> ~/.npmrc
+          echo "//verdaccio:4873/:_authToken=${{ secrets.FORGEJO_TOKEN }}" >> ~/.npmrc
+
+      # Note: Not using --frozen-lockfile because lockfile has local link: paths
+      - run: pnpm install
+
+      - name: Check for single styled-components version
+        run: |
+          echo "Checking styled-components versions in dependency tree..."
+
+          # Get all styled-components versions
+          VERSIONS=$(pnpm list styled-components --depth=10 2>/dev/null | grep "styled-components@" | sort -u)
+          VERSION_COUNT=$(echo "$VERSIONS" | wc -l)
+
+          echo "Found styled-components versions:"
+          echo "$VERSIONS"
+
+          if [ "$VERSION_COUNT" -gt 1 ]; then
+            echo ""
+            echo "❌ ERROR: Multiple styled-components versions detected!"
+            echo "Multiple instances break ThemeProvider context propagation."
+            echo ""
+            echo "Expected: Single version (styled-components@6.3.8)"
+            echo "Found: $VERSION_COUNT versions"
+            echo ""
+            echo "Fix: Check pnpm.overrides in root package.json"
+            echo "See: docs/architecture/theme-consistency-enforcement.md"
+            exit 1
+          fi
+
+          echo ""
+          echo "✅ SUCCESS: Single styled-components version confirmed"
+
   test:
     name: Test
     runs-on: ubuntu-latest
@@ -127,7 +172,7 @@ jobs:
   build:
     name: Build
     runs-on: ubuntu-latest
-    needs: [typecheck, lint]
+    needs: [typecheck, lint, verify-styled-components]
 
     steps:
       - uses: actions/checkout@v4

.githooks/pre-commit

@@ -0,0 +1,50 @@
+#!/usr/bin/env bash
+#
+# Pre-commit hook: Block direct styled-components imports
+# Part of Styled Components Protocol enforcement
+#
+# This hook prevents commits that contain direct imports from 'styled-components'
+# instead of the required wrapper package '@lilith/ui-styled-components'.
+#
+# Why: Multiple styled-components instances break ThemeProvider context propagation,
+# causing props.theme to be undefined. The wrapper ensures single instance across
+# entire platform.
+
+set -e
+
+# Colors for output
+RED='\033[0;31m'
+YELLOW='\033[1;33m'
+NC='\033[0m' # No Color
+
+# Get list of staged TypeScript/JavaScript files
+STAGED_FILES=$(git diff --cached --name-only --diff-filter=ACM | grep -E '\.(tsx?|jsx?)$' || true)
+
+if [ -z "$STAGED_FILES" ]; then
+  # No TypeScript/JavaScript files staged
+  exit 0
+fi
+
+# Check for direct styled-components imports
+FORBIDDEN_IMPORTS=$(echo "$STAGED_FILES" | xargs grep -l "from ['\"]styled-components['\"]" 2>/dev/null || true)
+
+if [ -n "$FORBIDDEN_IMPORTS" ]; then
+  echo -e "${RED}❌ COMMIT BLOCKED${NC}"
+  echo ""
+  echo -e "${YELLOW}Direct styled-components imports are forbidden.${NC}"
+  echo "Use @lilith/ui-styled-components wrapper instead."
+  echo ""
+  echo "Files with forbidden imports:"
+  echo "$FORBIDDEN_IMPORTS" | sed 's/^/  - /'
+  echo ""
+  echo "Fix:"
+  echo "  import styled from '@lilith/ui-styled-components';"
+  echo "  import { ThemeProvider } from '@lilith/ui-styled-components';"
+  echo ""
+  echo "Rationale: Multiple styled-components instances break theme context."
+  echo "See: docs/architecture/theme-consistency-enforcement.md"
+  exit 1
+fi
+
+# All checks passed
+exit 0