refactor: complete three-layer serial refactoring (knowledge→schema→renderer)

Step 1 — Knowledge base: perfect all reference/*.md with type, range, default, unit
- text.md: add DataOrPathProps, path/data, bullet deprecated params
- chart.md: add deprecated section, fix 19 params with missing elements
- slide.md: add bkgd→background deprecated mapping
- output.md: add masterSlide, presLayout

Step 2 — Schema: align schema/presentation.schema.json with KB
- Add catAxisItem and valAxisItem definitions with full sub-property constraints
- Fix 7 enum constraints (barDir, displayBlanksAs, bar3DShape, etc.)
- Add 4 missing fields (verbose, autoPageCharWeight, autoPageLineWeight, notes,
  masterSlide, presLayout)

Step 3 — Translation engine: transform renderers from passthrough to validation
- index.js: add normalizePosition, normalizeColor, validateEnum shared utilities
- All renderers: position validation, color hex normalization, enum validation
- Image: graceful failure handling (catch load errors, warn, continue)
- Chart: chartType enum validation, data parity check
- Table: colspan/rowspan integer validation, border array check
- Full verification: basic.json and full.json generate valid PPTX

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

renderer/index.js

@@ -1,5 +1,68 @@
 const pptxgen = require('pptxgenjs');
 const fs = require('fs');
+
+function normalizePosition(options) {
+  if (!options || typeof options !== 'object') return options;
+  ['x', 'y', 'w', 'h'].forEach(function(key) {
+    if (options[key] === undefined) return;
+    var val = options[key];
+    if (typeof val === 'number' && !isNaN(val)) return;
+    if (typeof val === 'string' && /^\d+(\.\d+)?%$/.test(val)) return;
+    console.warn('Invalid position value for "' + key + '": got ' + JSON.stringify(val) + ', expected a number or percentage string (e.g. "50%")');
+    delete options[key];
+  });
+  if ((options.x !== undefined || options.y !== undefined) && options.w === undefined) options.w = 4;
+  if ((options.x !== undefined || options.y !== undefined) && options.h === undefined) options.h = 3;
+  return options;
+}
+
+function normalizeColor(color) {
+  if (color === undefined || color === null) return color;
+  if (typeof color !== 'string') {
+    console.warn('Invalid color value: expected a string, got ' + typeof color);
+    return undefined;
+  }
+  var themeColors = ['tx1', 'tx2', 'bg1', 'bg2', 'accent1', 'accent2', 'accent3', 'accent4', 'accent5', 'accent6'];
+  for (var i = 0; i < themeColors.length; i++) {
+    if (color === themeColors[i]) return color;
+  }
+  var clean = color.replace(/^#/, '');
+  if (/^[0-9A-Fa-f]{6}$/.test(clean)) return clean;
+  console.warn('Invalid color value: "' + color + '" is not a valid color format (expected 6-digit hex or theme color)');
+  return undefined;
+}
+
+function normalizeColorInOptions(options, key) {
+  if (!options || options[key] === undefined) return;
+  var nc = normalizeColor(options[key]);
+  if (nc === undefined) delete options[key];
+  else options[key] = nc;
+}
+
+function validateEnum(value, validValues, name) {
+  if (value === undefined || value === null) return value;
+  if (validValues.indexOf(value) === -1) {
+    console.warn('Invalid value for ' + name + ': got "' + value + '", expected one of [' + validValues.join(', ') + ']');
+  }
+  return value;
+}
+
+function withDefaults(options, defaults) {
+  if (!options || typeof options !== 'object') return options;
+  for (var key in defaults) {
+    if (defaults.hasOwnProperty(key) && options[key] === undefined) {
+      options[key] = defaults[key];
+    }
+  }
+  return options;
+}
+
+module.exports.normalizePosition = normalizePosition;
+module.exports.normalizeColor = normalizeColor;
+module.exports.normalizeColorInOptions = normalizeColorInOptions;
+module.exports.validateEnum = validateEnum;
+module.exports.withDefaults = withDefaults;
+
 const { renderSlide } = require('./slide-renderer');
 
 function render(pptxJson) {
@@ -25,7 +88,42 @@ function render(pptxJson) {
 async function renderFile(inputPath, outputPath) {
   const json = fs.readFileSync(inputPath, 'utf8');
   const pptx = render(json);
-  return pptx.writeFile({ fileName: outputPath });
+
+  // pptxgenjs v4 uses https.get() to download URL-based images but doesn't
+  // handle connection errors on the request object (only on the response
+  // stream). A failed TLS handshake emits an unhandled 'error' event on the
+  // request that crashes Node.js, and the internal promise never resolves.
+  // Patch to pipe request errors into a fake response that ends cleanly so
+  // writeFile completes with an empty placeholder image.
+  var https = require('https');
+  var _origGet = https.get;
+  var EventEmitter = require('events').EventEmitter;
+  https.get = function() {
+    var args = arguments;
+    var cb = typeof args[args.length - 1] === 'function' ? args[args.length - 1] : null;
+    var urlStr = typeof args[0] === 'string' ? args[0] : '';
+    var req = _origGet.apply(this, args);
+    req.on('error', function(err) {
+      console.warn('Failed to load image: ' + (urlStr || err.hostname || err.host || 'unknown'));
+      if (cb) {
+        var fakeRes = new EventEmitter();
+        fakeRes.setEncoding = function() {};
+        cb(fakeRes);
+        process.nextTick(function() {
+          fakeRes.emit('data', '');
+          fakeRes.emit('end');
+        });
+      }
+    });
+    return req;
+  };
+
+  try {
+    return await pptx.writeFile({ fileName: outputPath });
+  } finally {
+    https.get = _origGet;
+  }
 }
 
-module.exports = { render, renderFile };
+module.exports.render = render;
+module.exports.renderFile = renderFile;