Add release notes for 3.6.0-rc3

[Copilot]

Documented changes between 3.6.0-rc2 and 3.6.0-rc3 covering 5 commits across 4 merged PRs.

Scope of changes:

• Workflow list pagination fixes (preserved page state during re-renders, refactored query parameter handling)
• Workflow designer node sizing improvements (minimum size enforcement, enhanced caching)
• Workflow instance viewer navigation fixes (workflow-as-activity double-click, journal item fallback loading)
• Elsa.Api.Client dependency update to 3.6.0-rc3

Release notes follow standard format with commit SHAs and PR references for traceability.

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