chore(web): CI cleanup — declare debugLog global, fix entity-unescape order, drop v3 from UI branding

- Add debugLog to the /* global */ headers of the six JS files that call it
  (defined in base.html's first inline script) — resolves the wall of
  "'debugLog' is not defined" ESLint errors failing the Codacy check.
- Fix the two js/double-escaping CodeQL alerts in app-shell.js: the
  entity-unescape chains decoded & before </>, so a value
  containing a pre-escaped "&amp;lt;" wrongly double-decoded to "<".
  &amp; now decodes last (standard order). Pre-existing bug, made visible
  when the inline scripts moved into scannable .js files.
- Page title / header drop the "- v3" suffix, matching the de-versioned
  user-facing URL.

The remaining 7 CodeQL alerts are pre-existing patterns newly visible to
scanning (CodeQL doesn't see inline template JS): 4 github.com/htmx.org
URL-substring checks (the htmx ones match error-message text, not URLs —
false positives in context) and 1 innerHTML XSS-through-DOM in the GitHub
install flow. Triage/fix deferred to a focused follow-up rather than
expanding this PR.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01KEZK1P1Q1fu5pcuVrkrCFZ

web_interface/static/v3/plugins_manager.js

@@ -1,3 +1,4 @@
+/* global debugLog */
 // ─── LocalStorage Safety Wrappers ────────────────────────────────────────────
 // Handles environments where localStorage is unavailable or restricted (private browsing, etc.)
 const safeLocalStorage = {