Code Review: Grade and Improve Roblox Luau Code Quality

-- BEFORE: multiple quality issues
function giveCurrency(player, amount)
    wait(0.1)
    local data = game:GetService("DataService").getData(player)
    data.coins = data.coins + amount
    player.leaderstats.Coins.Value = data.coins
end

-- AFTER: task library, cached service, type annotations, nil guards
local DataService = require(ServerStorage.Services.DataService)

local function giveCurrency(player: Player, amount: number): ()
    task.wait(0.1)
    local data = DataService.getData(player)
    if not data then return end
    data.coins += amount

    local leaderstats = player:FindFirstChild("leaderstats")
    local coinsValue  = leaderstats and leaderstats:FindFirstChild("Coins")
    if coinsValue then coinsValue.Value = data.coins end
end

-- GOOD: Single responsibility, clean public API
local InventoryService = {}

function InventoryService.addItem(player: Player, itemId: string, quantity: number): boolean
    -- implementation
    return true
end

function InventoryService.removeItem(player: Player, itemId: string, quantity: number): boolean
    -- implementation
    return true
end

return InventoryService

ServerScript (entry point)
  → GameService (orchestration)
    → InventoryModule (domain logic)
      → DataModule (persistence)

## Code Review Report

### Overall Grade: [A–F]

### Organization: [A–F]
- [Findings with file paths and specific issues]

### Code Quality: [A–F]
- [Findings by severity]

### Architecture: [A–F]
- [Findings with dependency diagrams if relevant]

### Security: [A–F]  (quick-check)
- [Findings with severity]

### Performance: [A–F]  (quick-check)
- [Findings with severity]

### Summary Statistics
- Total scripts reviewed:       X
- Deprecated API usages:        X
- Unvalidated remotes:          X
- Potential memory leaks:       X
- Circular dependencies:        X
- Duplicate code instances:     X

### Top 5 Priority Fixes
1. [Most impactful fix with specific code suggestion]
2. ...