feat: add wxPython accessibility specialist agent

[Orinks]

Problem

wxPython desktop apps have framework-specific accessibility pitfalls that generic agents miss (focus management, labeling semantics, keyboard flow, screen reader announcements, and custom control behavior).

Goal

Add a dedicated wxPython accessibility specialist agent that reviews code/PRs and returns actionable findings with concrete fixes.

Scope (v1)

• Detect missing/weak control labels, names, and accessible descriptions in wx widgets
• Keyboard-only navigation checks (tab order, trapped focus, missing accelerators)
• Screen reader behavior checks (state changes, status updates, dialog announcements)
• Dialog UX checks (modality, default action, escape handling, focus start)
• Baseline visual accessibility checks relevant to wx UI patterns (contrast and text scaling hotspots)

Deliverables

• New wxPython specialist agent profile + prompt template
• Docs page for running the agent on wx repositories
• Standardized report format (severity, file/line, rationale, fix suggestion)
• Regression checklist for NVDA/VoiceOver-style validation workflows

Acceptance Criteria

• Agent runs on a sample wx project and returns deterministic output
• Agent catches known seeded wx accessibility defects in sample fixtures
• Output is specific enough to implement directly (no vague advice-only reports)

Nice-to-have (post-v1)

• Optional autofix hints for common wx anti-patterns
• Rule packs for high-risk controls (custom draw, virtual lists, owner-drawn menus)

Proposed next steps

1. Create draft implementation PR scaffold (feat/wxpython-accessibility-agent)
2. Implement v1 rules + report schema
3. Validate on sample wx app and post findings back to this issue