Introduces dynamic background images for `BattleScene` based on the opponent's faction (Imperial, Raider, Bloodthirsty). The system:
- Defines a configuration of 3 variant assets per faction.
- Selects a random variant during the preload phase if the opponent's commander card is available.
- Renders the selected background with a dimming overlay in `create`, falling back to the solid color if no image is loaded or defined.
Includes new asset files: `imperial_03.png` and `raider_03.png`.
- **Combat Logic**: Refactored `swipe` to trigger on `preAttack`, dealing damage to all enemy cards and the commander while ignoring armor. Updated `data/skills.json` and card definitions in `data/cards.json` accordingly.
- **Animation**: Added `_animateSwipeSequence` in `BattleScene.js`. The animation spawns a rotating sprite (index 20) that flies sequentially to each target, playing impact sounds (`sfx_swipe_02`) and triggering HP loss/death animations per target.
- **Assets**: Added new audio files (`swipe_01.mp3`, `swipe_02.mp3`) and UI images for factions (`bloodthirsty`, `imperial`, `raider`). Updated the attack spritesheet.
- **Collection Scene**: Overhauled `CollectionScene.js` with a modern UI featuring:
- Filterable, scrollable card grid with hover tilt effects.
- Interactive card selection showing a large showcase view.
- CRT-style terminal that types out detailed card stats and skill descriptions character-by-character.
- Added `playerGoesFirst` state to `CombatEngine` to alternate turn order each round.
- Updated `beginTurn` and `beginCommit` to handle AI deployment based on the current initiative (opponent deploys first if they have initiative, otherwise after the player).
- Modified `_buildPendingAttacks` to respect the alternating attack order.
- Added `animateHPLoss` to `CardObject.js` for a visual HP reduction animation similar to the Berserk gain effect.
- Enhanced `_animateAttack` in `BattleScene.js`:
- Integrated sprite animations for attacks (gun turret) and explosions using new spritesheets.
- Synchronized HP loss and Berserk gain animations with the attack sprite completion.
- Added an "Attacks First" indicator icon next to the commander of the side with initiative.
- Updated `BootScene.js` to load the new `attacksFirst` UI image and `attacks` spritesheet.
- Updated `cards.json` and `skills.json` to trigger Berserk on damage dealt (`on_attack`) instead of on kill, adjusting descriptions accordingly.
- Modified `CombatEngine.js` to emit a `berserk` event after successful attacks and removed the previous kill-based logic.
- Enhanced `SkillProcessor.js` to apply Berserk attack power gains only when damage is dealt during an attack.
- Added `animateBerserkGain` in `CardObject.js` to visually display the ATK increase with scaling, a "+N" label, and smooth transitions.
- Overhauled `_animateAttack` in `BattleScene.js`:
- Cards now slide to the center and scale up during attacks, then return to their original positions.
- Added a "VS" image that appears between cards during the clash.
- Synchronized particle bursts, shakes, and damage numbers with the new centered animation timing.
- Integrated Berserk gain animation into the attack flow, rewinding ATK text before animating the increase.
- Added `vs.png` asset loading in `BootScene.js`.
Brian Fertig