fix: sync version metadata and remove stale legacy README API

[dev3Nigerian]

Summary

• sync pytempo.__version__ with pyproject.toml (0.3.1)
• make Sphinx release derive from pytempo.__version__ to avoid future drift
• remove stale README references to removed legacy APIs (create_tempo_transaction, patch_web3_for_tempo)
• update README examples list to match files that actually exist in examples/
• add tests/test_version.py regression tests for package/docs version consistency
• refresh uv.lock metadata so the editable pytempo package entry tracks 0.3.1

Problems Solved

• package runtime version was stale (0.3.0) while project metadata was 0.3.1
• docs release string was hardcoded to the stale version
• README instructed users to import APIs that were removed in v0.3.0
• lock metadata still pointed at an older editable package version

Verification

• uv run ruff check .
• uv run ruff format --check .
• uv run pytest -q (84 passed, 23 skipped)

Tradeoffs / Open Questions

• README now only documents the typed API and explicitly notes legacy API removal; no compatibility shim was reintroduced.