feat: Implement automated OpenAPI type generation

Add automated type synchronization from backend OpenAPI schema to frontend TypeScript types to prevent type drift and ensure runtime safety.

Changes:
- Add openapi-typescript as dev dependency
- Create npm scripts for type generation (generate:types) and validation (validate:types)
- Integrate type generation into build pipeline (runs before TypeScript compilation)
- Generate frontend/src/types/generated.ts from backend OpenAPI schema
- Add frontend/scripts/validate-types.sh for CI/CD validation
- Update Web-Development.md with type generation workflow documentation
- Update Backend-Development.md with OpenAPI schema sync requirements

Workflow:
1. Backend automatically exposes OpenAPI schema at /api/openapi.json (FastAPI built-in)
2. Frontend build runs 'npm run generate:types' to generate types from schema
3. Generated types are committed to version control
4. CI can run 'npm run validate:types' to fail builds if types drift

Fixes critical type safety issue where frontend types were manually maintained
and could become out of sync with backend Pydantic models.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

frontend/scripts/validate-types.sh

@@ -0,0 +1,45 @@
+#!/bin/bash
+# Validate that generated types match the committed types.
+# This script is designed to run in CI/CD pipelines to prevent type drift.
+# 
+# Exit codes:
+#   0 — types are in sync
+#   1 — types are out of sync
+#   2 — backend is not accessible
+#   3 — generation failed
+
+set -euo pipefail
+
+SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
+FRONTEND_DIR="$(dirname "$SCRIPT_DIR")"
+TYPES_DIR="${FRONTEND_DIR}/src/types"
+GENERATED_FILE="${TYPES_DIR}/generated.ts"
+TEMP_FILE=$(mktemp)
+trap "rm -f $TEMP_FILE" EXIT
+
+# Check if backend is accessible
+BACKEND_URL="${BANGUI_BACKEND_URL:-http://localhost:8000}"
+if ! curl -sf "${BACKEND_URL}/api/openapi.json" > /dev/null 2>&1; then
+  echo "❌ Backend not accessible at ${BACKEND_URL}/api/openapi.json" >&2
+  exit 2
+fi
+
+echo "📋 Validating OpenAPI schema types..."
+
+# Generate types to a temporary file
+if ! npx openapi-typescript "${BACKEND_URL}/api/openapi.json" -o "$TEMP_FILE" 2>&1; then
+  echo "❌ Failed to generate types from OpenAPI schema" >&2
+  exit 3
+fi
+
+# Compare with committed generated types
+if ! diff -u "$GENERATED_FILE" "$TEMP_FILE" > /dev/null 2>&1; then
+  echo "❌ Generated types differ from committed types" >&2
+  echo ""
+  echo "Run 'npm run generate:types' to update types, then commit the changes:"
+  diff -u "$GENERATED_FILE" "$TEMP_FILE" || true
+  exit 1
+fi
+
+echo "✅ Types are in sync with backend schema"
+exit 0