Fix markdownlint violations across documentation and samples

[Copilot]

Fixed 93 markdownlint violations across 25 markdown files in the repository.

Changes

• Code blocks: Added language specifications (bash, yaml, json, csharp, text) to 24+ fenced code blocks
• Headings: Fixed 7 heading level increments and style inconsistencies (h4→h2, h3→h2)
• Lists: Standardized 19 unordered list items from asterisks to dashes
• Tables: Fixed 13 column spacing issues (extra/missing spaces around pipes)
• Inline HTML: Escaped angle brackets in table cells (<string> → <string>)
• Formatting: Removed multiple consecutive blank lines, fixed blockquote spacing, removed trailing whitespace
• Links: Fixed invalid fragment references and replaced non-descriptive link text ("here" → descriptive text)
• Emphasis: Converted bold text used as headings to proper heading elements

All files now pass markdownlint validation.

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