[Epic] Sidecar validation

[djm81]

Why

Parent issue for sidecar validation (framework support, extractors). Use this issue to group and track sidecar work (e.g. Flask, FastAPI, Django).

What

• Area: Sidecar validation (specfact repro --sidecar, framework extractors)
• Purpose: Assign child issues and change proposals to this parent via Relationships or project Type grouping.
• OpenSpec: Changes under openspec/changes/sidecar-01-*. See openspec/CHANGE_ORDER.md.

Acceptance Criteria

• All sidecar-related issues are linked to this parent.
• Implementation order follows CHANGE_ORDER.md.