Tests: Un-skip and stabilize the deferred E2E specs

[jjeff]

Problem

12+ Playwright tests are currently `test.skip` with "complex to simulate" or "requires implementation" comments. These represent unverified behavior.

Inventory

File	Skipped tests	Reason given
`tests/e2e/delay-options.spec.ts`	3	"Complex delay simulation"
`tests/e2e/advanced-events.spec.ts`	3	onSort / onChange / onMove
`tests/e2e/basic-sortable.spec.ts`	2	hover effects, touch input
`tests/e2e/animation.spec.ts`	full `describe.skip`	"requires full drag-and-drop"
`tests/e2e/animation-visual.spec.ts`	1	unknown
`tests/e2e/drag-and-drop.spec.ts`	conditional skip on Mobile Chrome	dragAndDrop timeout
`tests/e2e/ghost-elements.spec.ts`	conditional skip on Mobile Chrome	dragAndDrop timeout

Acceptance criteria

• Each skipped test either passes, has a tracked sub-issue with a real reason, or is deleted.
• Mobile Chrome workaround documented or replaced with a per-browser test variant.
• Total `.skip` count in `tests/e2e` reduced to zero (or each remaining one cites a filed bug).