CMMS fork: Phase 6 polish — schema.html light theme + load-time IndexedDB wipe

- cmms-bridge.js: wipeProjectData() clears the project object stores (devices,
  boards, components, images, overlappedImages, nets, schemas, schemaComponents
  — not the KiCad symbol library) and resets studio.js's shared globals before
  the CMMS attachment ZIP is imported. The ZIP is the single source of truth for
  a CMMS board, so restoreDevice()'s merge path (which only de-dupes on a newer
  meta.lastModified, absent on CMMS-created boards) no longer accretes duplicate
  image/net rows across repeated opens. init() also stamps data-theme=light as
  well as =dark. All gated on PCBRETRACE_CONFIG — standalone untouched.
- schema.html: inline head script mirrors ?theme=light|dark (passed by studio.js
  on the iframe src) onto <html> and, for light, injects cmms-schema-light.css.
  Full no-op with no ?theme=.
- cmms-schema-light.css (new): [data-theme="light"]-gated override of
  schema.html's :root palette for the CMMS light theme. Canvas stays dark.
- studio.js: append ?theme=<active> to the schema.html iframe src.

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

docs/studio.js

@@ -1528,7 +1528,10 @@ function switchView(v) {
 				//	'contentWindow.location:', frame.contentWindow?.location?.href);
 				frame.contentWindow.postMessage(msg, '*');
 			};
-			frame.src = 'schema.html';
+			// CMMS fork: hand the schema iframe the active theme so its
+			// light-mode override sheet can match the CMMS (no-op standalone).
+			const _t = document.documentElement.getAttribute('data-theme');
+			frame.src = 'schema.html' + (_t ? '?theme=' + encodeURIComponent(_t) : '');
 			// console.log('[studio] frame clientWidth:', frame.clientWidth,
 			//	'clientHeight:', frame.clientHeight,
 			//	'offsetWidth:', frame.offsetWidth,