feat: add CI workflow to validate collection integrity

Adds scripts/validate.sh and .github/workflows/validate.yml that run on
every push to main and every PR. Checks:
- Entry completeness (DESIGN.md, preview.html, preview-dark.html present)
- DESIGN.md schema (all 9 numbered sections present)
- README badge count matches actual directory count
- README index lists every design-md/ directory
- Preview HTML has DOCTYPE, charset, and viewport meta

Closes #93

Author: Luc0-0

.github/workflows/validate.yml

@@ -0,0 +1,22 @@
+name: Validate Collection
+
+on:
+  push:
+    branches: [main]
+  pull_request:
+    branches: [main]
+
+jobs:
+  validate:
+    name: Collection Integrity Check
+    runs-on: ubuntu-latest
+
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+
+      - name: Make validate script executable
+        run: chmod +x scripts/validate.sh
+
+      - name: Run validation
+        run: ./scripts/validate.sh

scripts/validate.sh

@@ -0,0 +1,95 @@
+#!/usr/bin/env bash
+# validate.sh — checks collection integrity for awesome-design-md
+set -euo pipefail
+
+REPO_ROOT="$(cd "$(dirname "$0")/.." && pwd)"
+DESIGN_DIR="$REPO_ROOT/design-md"
+README="$REPO_ROOT/README.md"
+
+errors=0
+warnings=0
+
+red()    { printf '\033[31m%s\033[0m\n' "$*"; }
+yellow() { printf '\033[33m%s\033[0m\n' "$*"; }
+green()  { printf '\033[32m%s\033[0m\n' "$*"; }
+
+# ── 1. Check design-md directory exists ───────────────────────────────────────
+if [[ ! -d "$DESIGN_DIR" ]]; then
+  red "ERROR: design-md/ directory not found"
+  exit 1
+fi
+
+# ── 2. Entry completeness ─────────────────────────────────────────────────────
+echo "Checking entry completeness..."
+while IFS= read -r -d '' dir; do
+  site=$(basename "$dir")
+  for required in DESIGN.md preview.html preview-dark.html; do
+    if [[ ! -f "$dir/$required" ]]; then
+      red "  MISSING: design-md/$site/$required"
+      ((errors++)) || true
+    fi
+  done
+done < <(find "$DESIGN_DIR" -mindepth 1 -maxdepth 1 -type d -print0 | sort -z)
+
+# ── 3. DESIGN.md schema — all 9 sections present ──────────────────────────────
+echo "Checking DESIGN.md section schema..."
+while IFS= read -r -d '' file; do
+  site=$(basename "$(dirname "$file")")
+  for i in $(seq 1 9); do
+    if ! grep -q "^## $i\." "$file" 2>/dev/null; then
+      red "  MISSING section ## $i. in design-md/$site/DESIGN.md"
+      ((errors++)) || true
+    fi
+  done
+done < <(find "$DESIGN_DIR" -name "DESIGN.md" -print0 | sort -z)
+
+# ── 4. README badge count vs actual entry count ───────────────────────────────
+echo "Checking README badge count..."
+actual_count=$(find "$DESIGN_DIR" -mindepth 1 -maxdepth 1 -type d | wc -l | tr -d ' ')
+badge_count=$(grep -oP 'DESIGN\.md%20count-\K[0-9]+' "$README" || echo "0")
+
+if [[ "$badge_count" != "$actual_count" ]]; then
+  red "  MISMATCH: README badge shows $badge_count but $actual_count directories exist"
+  ((errors++)) || true
+else
+  green "  Badge count OK: $actual_count"
+fi
+
+# ── 5. README collection index vs directories ─────────────────────────────────
+echo "Checking README index sync..."
+while IFS= read -r -d '' dir; do
+  site=$(basename "$dir")
+  if ! grep -q "design-md/$site/" "$README"; then
+    yellow "  WARNING: design-md/$site/ not listed in README"
+    ((warnings++)) || true
+  fi
+done < <(find "$DESIGN_DIR" -mindepth 1 -maxdepth 1 -type d -print0 | sort -z)
+
+# ── 6. Preview HTML structure ─────────────────────────────────────────────────
+echo "Checking preview HTML structure..."
+for html_file in preview.html preview-dark.html; do
+  while IFS= read -r -d '' file; do
+    site=$(basename "$(dirname "$file")")
+    if ! grep -qi "<!DOCTYPE" "$file"; then
+      yellow "  WARNING: missing DOCTYPE in design-md/$site/$html_file"
+      ((warnings++)) || true
+    fi
+    if ! grep -qi 'charset' "$file"; then
+      yellow "  WARNING: missing charset in design-md/$site/$html_file"
+      ((warnings++)) || true
+    fi
+    if ! grep -qi 'viewport' "$file"; then
+      yellow "  WARNING: missing viewport in design-md/$site/$html_file"
+      ((warnings++)) || true
+    fi
+  done < <(find "$DESIGN_DIR" -name "$html_file" -print0 | sort -z)
+done
+
+# ── Summary ───────────────────────────────────────────────────────────────────
+echo ""
+if [[ $errors -gt 0 ]]; then
+  red "Validation failed: $errors error(s), $warnings warning(s)"
+  exit 1
+else
+  green "Validation passed: 0 errors, $warnings warning(s)"
+fi