[Milestone D] D-03: Thread AspxDataContext through tree builder

[csharpfritz]

Extend AspxComponentTreeBuilder to propagate data context through ItemTemplate rendering.

[github-actions]

🏗️ Squad Triage — Forge (Lead / Web Forms Reviewer)

Issue: #96 — [Milestone D] D-03: Thread AspxDataContext through tree builder
Assigned to: Forge (Lead / Web Forms Reviewer)
Reason: No specific domain match — assigned to Lead for further analysis

Team roster:

• Forge (Lead / Web Forms Reviewer) → label: squad:forge
• Cyclops (Component Dev) → label: squad:cyclops
• Beast (Technical Writer) → label: squad:beast
• Jubilee (Sample Writer) → label: squad:jubilee
• Rogue (QA Analyst) → label: squad:rogue
• Colossus (Integration Test Engineer) → label: squad:colossus
• Psylocke (Skills Engineer) → label: squad:psylocke
• Bishop (Migration Tooling Dev) → label: squad:bishop
• Ralph (Work Monitor) → label: squad:ralph

To reassign, remove the current squad:* label and add the correct one.

[csharpfritz]

Implemented in commits d0f0837 / db98986 on experiment/aspx-middleware. 398/398 tests passing.