[amitfin]

• Updated devcontainer to use Python 3.14 base image and new customization layout; removed custom Dockerfile
• Bumped GitHub Actions to Python 3.12–3.14 matrix, added workflow_dispatch, and updated action versions
• Adjusted release workflow trigger to only run on created releases and moved to Python 3.14
• Dropped Python <3.10 support, removed importlib-metadata backport, and set mypy target to 3.14
• Simplified package metadata import in __init__
• Added typed XDATA structure with TypedDict
• Replaced deprecated coroutine checks and UTC timestamp calls
• Stabilized and sped up tests: shorter shutdown polling, removed sleeps, deterministic test-case data, socket connect/recv timeouts, and skipped flaky NULL+altered-key case
• Updated tox envlist and gh-actions mapping to 3.12–3.14