BACK-476 - Fix-inline-code-HTML-escaping-in-markdown-renderer

[kuwork]

Summary

Fixes double HTML-entity encoding inside inline code and fenced code blocks across all views that use the MermaidMarkdown renderer (wiki, task details, documentation, decisions, and file previews).

The sanitizeMarkdownSource helper was escaping < to < indiscriminately across the entire markdown source. Because code regions are already rendered verbatim by the Markdown engine, this caused users to see <id> instead of <id> inside inline code like `<id>`.

The fix collects protected ranges for fenced code blocks and inline code spans before running the < escape replacement, skipping any match that falls inside a code region.

Related Tasks

closes BACK-476

📋 Important: All PRs must have an associated task in the backlog.

• If no task exists, create one first using: backlog task create "Your task title"
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Task Checklist

• I have created a corresponding task in backlog/tasks/
• The task has clear acceptance criteria
• I have added an implementation plan to the task
• All acceptance criteria in the task are marked as completed

Testing

• bunx tsc --noEmit passes with no new errors.
• Verified manually that inline code containing < (e.g. `backlog task <id>`) now renders as <id> instead of <id> on wiki pages.
• Confirmed that fenced code blocks with < are also preserved correctly.
• Confirmed that regular text outside code regions still has <Something> escaped to prevent accidental HTML tag parsing.
• Confirmed that URI autolinks (<mailto:...>) and email autolinks continue to work.