fix(web): refine prompt anchor and sidebar branding (#201)

Replace the prompt timeline with a compact line index that expands to
prompt-only navigation while keeping clear of the composer.

Use theme-specific Pythinker banners in the shared desktop sidebar and
rebuild the committed web bundle.

Task: tasks/todo.md#prompt-anchor-redesign

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## Related Issue

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Resolve #(issue_number)

## Problem

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## What changed

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## Checklist

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[CONTRIBUTING](https://github.com/PyModel/pythinker-code/blob/main/CONTRIBUTING.md)
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- [ ] I have linked a related issue (external PRs: the issue must have a
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<!-- This is an auto-generated comment: release notes by coderabbit.ai
-->
## Summary by CodeRabbit

- **New Features**
- Added a compact prompt index beside conversations, with hover/focus
expansion and improved responsive behavior.
- Added light and dark theme-matched Pythinker sidebar banners with
updated branding.
- Expanded diagram support, including quadrant, railroad, requirement,
Sankey, state, timeline, Venn, Wardley, XY chart, and other
visualizations.
- Added editor support for Razor, TypeScript, XML, YAML, and enhanced
JavaScript/TypeScript language services.

- **Bug Fixes**
- Improved resilience when browser theme-detection APIs are unavailable.
  - Refreshed bundled assets for more reliable web application loading.
<!-- end of auto-generated comment: release notes by coderabbit.ai -->

Author: elkaix

.changeset/compact-prompt-anchor.md

@@ -0,0 +1,5 @@
+---
+"@pymodel/pythinker-code": patch
+---
+
+Make the chat prompt anchor a compact line index that expands to prompt labels.

.changeset/theme-sidebar-banners.md

@@ -0,0 +1,5 @@
+---
+"@pymodel/pythinker-code": patch
+---
+
+Use theme-matched Pythinker banners in the sidebar.

apps/pythinker-code/dist-web/.web-bundle-manifest.json

@@ -1,4 +1,4 @@
 {
-  "sourceHash": "b515297a2d3ed0f85c3a7e6c4960370e6e4c6eae60e6e92d1244a0d109b5320f",
-  "sourceFileCount": 402
+  "sourceHash": "7c44db902d1a4f2eaea0c303444679df09333a4eca33d9beccef0f67adf21a31",
+  "sourceFileCount": 404
 }