Hard-level responsive grid: adapt rows/cols by orientation (portrait vs. landscape)

[pekomon]

Summary
Hard difficulty grid should adapt to device orientation to keep cells readable. In portrait, use a tall grid; in landscape, use a wide grid. Keep mine density consistent with the current Hard baseline.

Details

• Portrait: 14 (cols) x 24 (rows)
• Landscape: 24 (cols) x 14 (rows)
• Mines: keep ~Hard density (~20.625%) calculated from the original 30x16 with 99 mines → round(0.20625 * cols * rows) ≈ 69 for 14x24 and 24x14.
• Apply only to Hard difficulty. Easy/Medium remain as-is (Phase 1 scope was UI baseline).
• Orientation detection must be multiplatform-safe. Suggested approach:
  • Common: use BoxWithConstraints to infer aspect ratio (width > height → landscape).
  • Derive grid (cols, rows) from aspect ratio per rules above.
  • Avoid platform-specific APIs in commonMain.

Acceptance Criteria

• Hard difficulty renders 14x24 in portrait and 24x14 in landscape.
• Mines count uses a density consistent with Hard (≈20.6%), rounded to nearest integer.
• No crashes on orientation changes; grid re-composes correctly.
• Spotless/KtLint/Detekt pass; no global rule changes.
• Works on Android, iOS, Desktop, and Wasm.

Non-Goals (this issue)

• Zooming/pinch-to-zoom
• Persisted settings or dynamic scaling beyond the two layouts

Labels

• project:minesweeper, phase:2, enhancement, ux