Adds beta Uniswap v4 support: swaps, exact-input/output quotes, price impact, StateView reads, pool discovery, and position/liquidity lifecycle operations.

Adds a dedicated v4 guide and runnable mainnet-fork examples, migrates the v1–v3 suite from Ganache to Anvil, and updates the project baseline to Python 3.12. Native ETH in v4 uses the zero address; see uniswap-python.com/v4.html for the PoolKey and migration details.

Merged PRs

• V4 support by @liquid-8 in #418
• docs: update README with v4 support by @TimeToBuildBob in #470
• docs: v4 narrative guide, v2/v3 examples, and runnable example tests by @TimeToBuildBob in #471
• refactor(tests): replace ganache with anvil for v1–v3 tests by @TimeToBuildBob in #472
• fix: avoid duplicate WETH in swap path when input/output is WETH (closes #363) by @botbikamordehai2-sketch in #459
• build(deps): bump minimum Python to 3.12, update deps, drop typed_ast by @TimeToBuildBob in #473

Full Changelog: v0.7.2...v0.8.0