[survey] Add collaborative survey design workspace with real-time co-editing

[AI:Feature-Suggestion] ## Methodology This feature was identified through analysis of modern collaborative software trends and gaps in the current survey application. Tools like Figma, Notion, and Google Docs have revolutionized collaborative creation, but survey platforms remain largely single-user experiences. The current application has user authentication infrastructure ready but lacks any collaborative features. This represents a significant market opportunity, as team-based survey creation is increasingly common in organizations but poorly supported by existing tools. ## Specification ### Problem/Opportunity Survey creation is often a team effort involving researchers, designers, stakeholders, and subject matter experts, but current survey tools treat it as a single-user activity. This leads to: - Inefficient email-based feedback loops and version control issues - Loss of context and rationale behind survey design decisions - Difficulty in maintaining brand consistency acros