chore(ios-runner): delete the unreachable synthesized continuous drag profile

[thymikee]

Summary

Removes the synthesized .continuous (smoothstep) drag profile. Nothing could reach it: the only daemon drag producer is macOS-only and never sets synthesized.

• Removed the ObjC continuous path, smoothstep, and the frame-count export (with its test), plus the ADR/Two iOS drag synthesis strategies now coexist; document or reconcile them #1586 comment, which only described smoothstep.
• Removed the Swift .continuous case, and in executeDragGesture the synthesized: flag and the second synthesized block. Profile and policy now travel as one optional.
• .fastSwipe and .controlledScroll are unchanged byte for byte. ADR 0013 and 0011 now describe the lanes that remain.

Two ways the current code differs from the issue: a runner drag that sets synthesized now runs a plain coordinate drag, and a non-iOS gesture endpoint-hold plan (which the daemon never sends) no longer reports gestureFallback.

8 files, +33/−152. Closes #2790

Validation

Rebased onto main at a913cb222. Signed macOS host lane: 236/236 at 3b3fd2766 (+2 tests from main). check:affected --run is green at the stack head 60e533284. The evidence below is from before the rebase.

Tested at a72db6538.

• Gates: check:affected --run, check:xctest-selection, and format:check pass. grep -rni continuous in the runner UITests finds only a text-entry comment.
• Host-lane XCTest (locally signed): 234/234 pass.
• iPhone 17 Pro simulator: the 01-navigation-scroll (swipe plus scroll edges), 02-checkout-release, gesture-pan-duration, and drag replays pass. Runner log shows agent-device-controlled-scroll and agent-device-swipe records.
• The E2E smoke passed its scroll steps. snapshot-depth-frontier failed because it expects the AX-bridge backend and got xctest here; that is unrelated snapshot code, so CI is authoritative.
• Review: fixed the stale docs, the dead policy argument, and the fixture flag. Rejected inlining the sampler (it must stay byte-identical) and rejecting synthesized on drag (that would be a new compatibility path).

🤖 Generated with Claude Code

[github-actions]

Size Report

Metric	Base	Current	Diff
Installed (including dependencies)	4.80 MB	4.80 MB	-4.1 kB
Package (unpacked)	4.80 MB	4.80 MB	-4.1 kB
Package (download)	1.43 MB	1.43 MB	-499 B

Startup median (7 runs, lower is better):

Scenario	Base	Current	Diff
CLI --version	27.8 ms	27.6 ms	-0.2 ms
CLI --help	83.5 ms	78.7 ms	-4.8 ms

[thymikee]

Reviewed at a72db65: the code looks correct. Every synthesizedDragAt caller passes profile explicitly, and nothing on the TS side can still select the deleted continuous drag profile. The CI smoke scroll top step ran through the changed executeDragGesture lane and passed. One small note: the long line in docs/adr/0013-unified-gesture-plans.md:129 could be rewrapped to match the paragraph.

The Smoke Tests failure in smoke:regular-visible-depth-frontier looks unrelated. It fails on the AX-bridge snapshot assertion, this diff does not touch snapshot or bridge code, and the same assertion fails on #2820. That lane still needs a fix or a rerun on main before merge.