Visual power-ups — special effects for notable GitHub events

[Empreiteiro]

Description

Add dramatic visual effects on the territory grid when significant GitHub events occur, making the battle more exciting to watch.

Proposed Effects

Event	Visual Effect
PR Merged	Explosion/burst animation at the territory expansion point — cells flash bright and radiate outward
Commit streak (3+ commits in short window)	Lightning bolt / electric effect across the player's territory
Issue opened	Ripple wave effect from the new cell
Code Review	Shield/glow pulse on the player's existing territory
First score (player goes from 0 to >0)	"FIRST BLOOD" text banner across the grid
Overtake (player passes the leader)	Screen shake + "OVERTAKE!" floating text
Large commit (10+ files changed)	Meteor/comet trail animation

Details

• Detection: Compare prevBattle vs battle state (same mechanism as current floating text) to detect notable events
• Canvas effects: Rendered on the territory grid canvas layer with requestAnimationFrame
• Sound effects (optional): Short audio cues for major events (can be toggled off)
• Duration: Effects last 1-2 seconds and don't block grid interaction
• Mobile: Effects should be lighter/simpler on mobile to preserve performance

Acceptance Criteria

• At least 4 distinct visual effects for different event types
• Effects render smoothly on the canvas without frame drops
• Notable events detected from battle state diff
• Effects are visually clear and don't obscure the territory grid
• Performance acceptable on mobile devices