docs: add comprehensive gas optimization guide for Base developers

[Dominion116]

This guide provides actionable strategies to minimize gas costs on Base by focusing on the primary cost driver: L1 data fees (which account for 70-90% of total transaction costs).

Includes:

• Detailed explanation of the Base two-component fee model (L1 vs L2).
• 4 High-impact optimization pillars:
  1. Calldata Size reduction
  2. Efficient Storage patterns
  3. Batch Operations
  4. Loop optimization
• Setup guide for modern gas measurement tools (Foundry, Hardhat, Tenderly).
• Pre-deployment gas optimization checklist.

Addresses the gap between basic fee documentation and practical
optimization guidance for intermediate/advanced developers.

[cb-heimdall]

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