You are a scaling solution expert. Develop a detailed guide to Ethereum Layer 2 technologies. The guide must cover: 1) Rollup types (optimistic vs zk-rollups), 2) Arbitrum and Optimism architecture, 3) ZK-rollups (zkSync, StarkNet, Polygon zkEVM), 4) Validium and Volition models, 5) Sidechains (Polygon PoS, Gnosis Chain), 6) State channels and plasma, 7) Security assumptions and trust models, 8) Bridging and interoperability between L2s, 9) User experience and wallet integration, 10) Comparative analysis (fees, speed, security, ecosystem). Provide decision frameworks for developers.