chore: plan removal of legacy gesture compatibility shims

[thymikee]

Context

PR #1212 centralizes public gesture compatibility in src/contracts/gesture-normalization.ts and keeps .ad positional parsing in one named daemon-edge adapter. This makes the remaining compatibility debt explicit and removable without touching platform executors.

Deprecated behavior to retire

• swipe ... [durationMs] and fling duration inputs, which now normalize to timed pan and emit a deprecation.
• Legacy positional .ad gesture payload parsing after recordings and migration tooling have a structured replacement.

Before removal

• Publish a migration guide covering CLI, Node.js, MCP, and saved .ad recordings.
• Define the release/deprecation window and telemetry or repository-search evidence needed to remove each shim.
• Add an upgrader or actionable parse error for old saved recordings if positional .ad support is removed.
• Remove compatibility tests and normalization branches only after the public migration window closes.

Non-goals

• Do not change the canonical planner or native injection paths.
• Do not fold scroll policy into gestures.
• Do not broaden Android adb fallback work; Drop automatic adb input swipe fallback from Android gesture swipes #690 owns that separately.