test: record context menu accessibility spike

[leoafarias]

Summary

• records disposable V0/V1 trigger, focus, lifecycle, and geometry evidence against Link PR feat: add naked link #65
• preserves the real child role and behavior while testing secondary click, long press, keyboard entry, focus restoration, and edge positioning
• changes only five spike/evidence files; no production API or package export is added

Findings

• the Link child passes the automated node/action contract
• SelectableText and the generic row fail the proposed V1 semantic/action contract
• SelectableText also prevents wrapper secondary-click and physical-long-press opens
• same-gesture touch selection is not proven
• D-03 remains open; production Context Menu is not authorized

Verification

• Flutter 3.41.0, 3.41.2, and 3.44.6: 15 focused, 4 flutter-tester integration, and 67 Menu/Select/Popover regression tests pass on each SDK
• Flutter 3.41.2 full analyze: clean
• macOS 26.5.2: 4/4 pass, exit 0
• Chrome 150: all in-app tests report pass, but host result/teardown hangs and requires interruption; this is recorded as infrastructure-incomplete, not a clean target pass

Remaining blockers

VoiceOver, TalkBack, and headed Chrome accessibility-tree sessions are UNRUN. This PR is based on feat/naked-link and should be retargeted to main only after PR #65 merges.

[leoafarias]

Closing — the findings are worth keeping, the scaffolding isn't.

This adds 1,899 lines across five *_spike* files, all under packages/example/, and zero library code. Its own summary calls the evidence "disposable."

Merged, it becomes a permanent fixture nothing imports, that CI must keep compiling, and that silently drifts as the components beneath it change. A year from now nobody will know whether it still holds.

Recording the findings here so they survive the close:

• the Link child passes the automated node/action contract
• SelectableText and the generic row fail the proposed V1 semantic/action contract
• SelectableText also prevents wrapper secondary-click and physical-long-press opens
• same-gesture touch selection is not proven
• D-03 remains open; production Context Menu is not authorized

That last point is the outcome: the spike concluded don't build it yet. It did its job, and the conclusion is what the next attempt needs — not the harness that produced it.

Full detail stays in the branch (context_menu_accessibility_at_results.md) if it's needed again.