Strict Rules & Blocking UI (Part 3)

Status: Completed

Integrate Strict Actions (PLAY_LAND, CAST_SPELL) with precise positioning.
Implement Blocking UI including visual feedback (Attacking/Blocking badges, Rings).
Implement Drag-and-Drop Targeting Logic (Spell -> Target, Blocker -> Attacker).
Implement Visual "Targeting Tether" overlay.

Positioning: Updated playLand and castSpell to accept {x, y} coordinates.
Stack Resolution: Updated resolveTopStack to respect the stored resolution position when moving cards to the battlefield.
Action Handling: Updated GameManager to pass position payload to the engine.

Drop Logic:
- handleZoneDrop: Detects drop on "Battlefield". Differentiates Land (Play) vs Spell (Cast). Calculates relative % coordinates.
- handleCardDrop: Detects drop on a Card.
  - If declare_blockers step: Assigns blocker (drag My Creature -> Opponent Creature).
  - Else: Casts Spell with Target.
- handlePlayerDrop: Detects drop on Opponent Avatar -> Cast Spell with Target Player.
Blocking Visualization:
- Opponent Cards: Show "ATTACKING" badge (Red Ring + Shadow) if attacking === property.
- My Cards: Show "Blocking" badge (Blue Ring) if in local proposedBlockers map.
Targeting Tether:
- Implemented tether state (startX, currentX, etc.).
- Added onDrag handler to CardComponent to track HTML5 DnD movement.
- Rendered Full-screen SVG overlay with Bezier curve (Q command) and arrow marker.
- Dynamic styling: Cyan (Spells) vs Blue (Blocking).

Layer System: Implement 7-layer P/T calculation for accurate power/toughness display.
Mulligan System: Implement Strict Mulligan rules.
Token Creation: Support creating tokens.