Bump runtime to Python 3.14

[spalen0]

Follow-up to #255 — split out per review feedback so the Docker packaging PR doesn't conflate runtime bump with new packaging.

Scope

• pyproject.toml:
  • requires-python = ">=3.14"
  • tool.ruff.target-version = "py314"
  • tool.mypy.python_version = "3.14"
• New .python-version at repo root containing 3.14 (so uv python install and local uv invocations pick it up automatically)
• uv lock regenerated against 3.14
• docker/Dockerfile (landed in Dockerize monitoring scripts (first PR: packaging + scheduler) #255): FROM python:3.14-slim for both builder and runtime stages
• Existing workflows (hourly.yml, daily.yml, weekly.yml, multisig-checker.yml, tests.yml) use uv python install which honours .python-version — no explicit version pin needed

Why now

We're shipping a fresh Docker image (#255) and a 2026 deployment; no reason to bake in a two-year-old runtime. Python 3.14 has been GA since Oct 2025 (~7 months) and all heavy deps in pyproject.toml (web3 7.x, pydantic 2.x, aiohttp 3.13.x, eth-account 0.13) ship 3.14 wheels.

Verification

• uv sync succeeds with .python-version = 3.14
• uv run pytest tests/ — full suite passes on 3.14
• uv run mypy . — clean with python_version = "3.14"
• uv run ruff check . and uv run ruff format --check . — clean with target-version = "py314"
• docker compose run --rm monitor python --version — Python 3.14.x
• One full hourly run via docker compose run --rm monitor python -m automation run hourly — exits 0

Sequencing

Lands after #255 so the Docker setup is proven working on the existing 3.12 runtime first; runtime bump can then be tested in isolation.