Address PR review findings for history exploration feature

Fix all blockers, major, and minor issues from hu-ahmed's review:

Blockers:
- B1: Make tab-sync guard async-safe via setTimeout(0) to survive
  Bootstrap's async shown.bs.tab events
- B2: Fix toDatetimeLocalValue to properly convert UTC to local
  timezone, preventing 404s for non-UTC users
- B3: Add Environments.addChangeListener to thingsHistory and
  thingUpdates to close SSE streams on environment switch

Majors:
- M1: Add fetch token to prevent stale diff responses from
  overwriting newer state
- M2: Wrap JSON.parse in onHistoricalMessage in try/catch
- M3: Validate from <= to range before opening SSE stream
- M4: Add missing .max constraint on historicalFromRevision input
- M5: Add thingId guard in thingsHistory probe callback
- M6: Restore Ace.Editor type annotations in policy files
- M7: Scope number input CSS to history/diff containers
- M9: Add MAX_MESSAGES cap (5000) with user notification
- M10: Use closest('tr') for robust row click handling
- M11: Return promises from refreshThingAtRevision/Timestamp,
  update banner on error
- M12: Call thingsDiff.ready() before registering listeners
- M13: Show toast on unexpected historical stream error

Minors:
- Extract shared probeOldestRevision helper to things.ts
- Extract shared toDatetimeLocalValue to utils.ts
- Deduplicate HISTORY_FIELDS constant (export from things.ts)
- Use structuredClone instead of JSON roundtrip
- Make historyModeActive a getter (isHistoryModeActive)
- Fix Term[] return type (was mistyped [Term?] tuple)
- Use Bootstrap Collapse API instead of classList manipulation
- Add AceDiff destroy() support, reuse SVG in minimap
- Pin ace-diff version exactly (4.0.0)
- Add null safety for sibling.parentElement
- Type messages/filteredMessages as any[]
- Cast ace as proper type instead of any
- Remove unused Time Travel button from Diff view
- Fix minimap click scroll bounce (disable animation)

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: thjaeckle

ui/main.scss

@@ -323,15 +323,18 @@ button.busy .spinner-border {
 }
 
 /* Revision picker alignment: force fixed sizes to align stacked rows */
-.input-group input[type="number"] {
+#collapseThings .input-group input[type="number"],
+#collapseThingUpdates .input-group input[type="number"] {
   flex: 0 0 80px !important;
   width: 80px !important;
   padding-right: 6px !important;
   -moz-appearance: textfield !important;
 }
 
-.input-group input[type="number"]::-webkit-outer-spin-button,
-.input-group input[type="number"]::-webkit-inner-spin-button {
+#collapseThings .input-group input[type="number"]::-webkit-outer-spin-button,
+#collapseThings .input-group input[type="number"]::-webkit-inner-spin-button,
+#collapseThingUpdates .input-group input[type="number"]::-webkit-outer-spin-button,
+#collapseThingUpdates .input-group input[type="number"]::-webkit-inner-spin-button {
   -webkit-appearance: none;
   margin: 0;
 }

ui/main.ts

@@ -95,9 +95,8 @@ document.addEventListener('DOMContentLoaded', async function() {
       itemsId: 'tabItemsThing',
       contentId: 'tabContentThing',
     });
-  Things.addChangeListener(thingsDiff.onThingChanged);
-  Things.addHistoryModeChangeListener(thingsDiff.onHistoryModeChanged);
   await thingsDiff.ready();
+  Things.addChangeListener(thingsDiff.onThingChanged);
 
   const attributesDiff = SubDiff({
       itemsId: 'tabItemsAttribute',

ui/modules/policies/policiesJSON.ts

@@ -12,6 +12,7 @@
  */
 
 import * as ace from 'ace-builds/src-noconflict/ace';
+import { Ace } from 'ace-builds';
 import * as API from '../api.js';
 import * as Environments from '../environments/environments.js'
 import * as Utils from '../utils.js';
@@ -30,7 +31,7 @@ let dom: DomElements = {
   selectPolicyJSONTemplate: null,
 };
 
-let policyEditor;
+let policyEditor: Ace.Editor;
 
 export function ready() {
 

ui/modules/policies/policiesResources.ts

@@ -12,6 +12,7 @@
  */
 
 import * as ace from 'ace-builds/src-noconflict/ace';
+import { Ace } from 'ace-builds';
 import * as API from '../api.js';
 import * as Utils from '../utils.js';
 import { CrudOperation, CrudToolbar } from '../utils/crudToolbar.js';
@@ -35,7 +36,7 @@ let dom : DomElements = {
   crudResource: null,
 } ;
 
-let resourceEditor;
+let resourceEditor: Ace.Editor;
 
 export function ready() {
   Utils.getAllElementsById(dom);

ui/modules/policies/policiesSubjects.ts

@@ -12,6 +12,7 @@
  */
 
 import * as ace from 'ace-builds/src-noconflict/ace';
+import { Ace } from 'ace-builds';
 import * as API from '../api.js';
 import * as Utils from '../utils.js';
 import { CrudOperation, CrudToolbar } from '../utils/crudToolbar.js';
@@ -33,7 +34,7 @@ let dom: DomElements = {
   crudSubject: null,
 } ;
 
-let subjectEditor;
+let subjectEditor: Ace.Editor;
 
 export function ready() {
   Utils.getAllElementsById(dom);

ui/modules/things/subDiff.ts

@@ -29,7 +29,7 @@ export function SubDiff(targetTab, title: string) {
   let pendingRight: string | null = null;
   let onActivatedCallback: ((link: HTMLAnchorElement) => void) | null = null;
 
-  return { ready, update, getTabLink, setOnActivated };
+  return { ready, update, getTabLink, setOnActivated, destroy: destroyDiff };
 
   async function ready() {
     const tabId = Utils.addTab(
@@ -82,7 +82,7 @@ export function SubDiff(targetTab, title: string) {
       diffInstance.diff();
     } else {
       diffInstance = new AceDiff({
-        ace: ace as any,
+        ace: ace as unknown as { edit: typeof ace.edit },
         element: container,
         mode: 'ace/mode/json',
         theme: null,
@@ -105,4 +105,11 @@ export function SubDiff(targetTab, title: string) {
       });
     }
   }
+
+  function destroyDiff() {
+    if (diffInstance) {
+      diffInstance.destroy();
+      diffInstance = null;
+    }
+  }
 }