* feat(ui-tui): resolve links to readable page titles
Mirror desktop pretty-link behavior in the TUI by resolving HTTP links to page titles with shared caching and safe fetch filters, plus slug-based fallbacks so chat links stay readable even when title fetch fails.
* refactor(ui-tui): tighten link-title fallback handling
Clean up the link-title resolver by hardening in-flight cleanup and clarifying title length limits, while adding focused coverage for HTML entity decoding and markdown-label fallback behavior.
* fix(ui-tui): block private-network targets in title fetches
Prevent automatic link-title resolution from requesting local or private hosts by rejecting RFC1918, link-local, ULA, and intranet-style hostnames before fetch, and add regression coverage for blocked host patterns.
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