Prepare source code for SwiftLint phase one

[austin-smith]

What Changed

• Removed unsafe force unwraps and replaced them with explicit optional handling.
• Applied focused formatting cleanup to source and test files that were expected to trigger initial lint findings.
• Added complete card accessibility names and corrected VoiceOver exposure for stock, waste, foundations, free cells, tableau run origins, exposed face-down cards, drag states, and animation overlays.
• Added selected-state accessibility feedback to actionable card and pile controls.

Why

This is phase one of the source-only preparation for #38. It addresses straightforward and meaningful findings before SwiftLint configuration or CI enforcement is introduced.

This PR intentionally does not add SwiftLint, a lint configuration, CI integration, baseline files, suppressions, or calibrated metric thresholds.

UI Changes

• VoiceOver now announces full rank-and-suit card names.
• Hidden, buried, dragged, and animated cards are excluded from the accessibility tree.
• Empty waste is no longer exposed as a no-op button.
• Valid tableau run origins and exposed face-down Klondike cards remain actionable.
• Waste, foundation, free-cell, and tableau controls announce selected state.

Validation

• macOS tests: 89 executed, 2 intentional fixture-generator skips, 0 failures.
• Generic iOS Simulator build: succeeded.
• git diff --check: passed.
• Final structured autoreview: clean with no actionable findings.

Related to #38.