fix(ui): remove stray sidebar character, fix RSS stylesheet and Feedly URLs, optimize TBT

[kascit]

Summary of Fixes

1. Sidebar Stray Character:

   • Removed stray Chinese character 厚 from templates/macros/sidebar.html (line 72).
   • Audited all templates, content, and scripts to confirm zero remaining stray characters.

2. RSS XML Stylesheet:

   • Changed static/rss.xsl XSLT version declaration from version="3.0" to version="1.0". Browser XSLT engines (e.g. libxslt in Chrome, Firefox, Safari) only support XSLT 1.0; declaring 3.0 caused stylesheet parsing errors and fallback to raw unstyled XML.

3. Feedly Subscription URLs:

   • Fixed double-encoded feed%2F in Feedly subscription links across archive.html, taxonomy_list.html, and taxonomy_single.html to standard feed/.

4. TBT & Long Task Performance Optimization:

   • Streamlined main.js initialization into three progressive lifecycle stages:
     • Phase 1 (Immediate): Core UI shell sync and navbar dropdowns.
     • Phase 2 (After First Paint): High-priority visual enhancements (tooltips, code blocks, visible page enhancements).
     • Phase 3 (Idle): Deferred non-critical background services and listeners (telemetry, search loader, shortcuts, webmcp, comments, etc.).
   • Eliminates main-thread blocking time during critical paint.

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