fix: jsocket reconnect lifecycle 2.0.2

[chris-piekarski]

This PR hardens jsocket connection lifecycle handling and removes an avoidable reconnect penalty after JsonClient.close(). It also
improves server-side socket/wakeup cleanup and bumps the package version to 2.0.2.

What Changed

• jsocket/jsocket_base.py
• JsonClient.connect() now pre-checks socket state and recreates a fresh socket when the current fd is closed (fileno() == -1)
  before attempting connect().
• Avoids the forced first-attempt Bad file descriptor error + 3s backoff cycle when reusing the same client object after close().
• Keeps retry/backoff behavior for genuine connection failures.
• _send() now treats OSError/zero-byte sends as broken connection and closes cleanly.
• Added _is_listening tracking so server listen() is idempotent and listener state is reset on bind/close.
• jsocket/tserver.py
• Wakeup socket fallback now closes intermediate sockets reliably on failure/success paths.
• ServerFactory now creates worker threads only after a successful accept/handoff.
• Accept-loop logging keeps non-timeout unexpected failures at exception level; shutdown path remains quiet (debug).
• tests/test_additional_coverage.py
• Added regression test to verify reconnecting with a previously closed client socket does not hit backoff sleep.
• jsocket/_version.py
• Version bumped from 2.0.1 to 2.0.2.

Behavioral Impact

• Reusing a JsonClient instance after close() is now fast-path recoverable (fresh socket created before dialing), instead of
  guaranteed initial failure + delay.
• Server/listener lifecycle is more robust under churn and shutdown.

Validation

• pytest -q tests/test_additional_coverage.py::test_client_connect_failure_returns_false tests/
  test_additional_coverage.py::test_client_connect_recreates_closed_socket_without_backoff (1 passed, 1 skipped in sandboxed env).
• pytest -q tests/test_additional_coverage.py::test_serverfactory_accept_error_branch tests/
  test_additional_coverage.py::test_serverfactory_accept_timeout_and_close_branches (1 passed, 1 skipped in sandboxed env).

[Copilot]

Pull request overview

This PR hardens jsocket client/server socket lifecycle behavior to avoid unnecessary reconnect backoff after JsonClient.close(), and improves server-side cleanup and accept-loop behavior while bumping the package version to 2.0.2.

Changes:

• JsonClient.connect() now recreates sockets proactively when the existing fd is closed, avoiding a guaranteed initial failure/backoff after reuse.
• _send() treats OSError/zero-byte sends as a broken connection and closes cleanly; server listening is made idempotent via _is_listening.
• tserver wakeup-socket fallback cleanup and ServerFactory accept/worker-spawn sequencing are improved; adds a regression test and bumps version.

Reviewed changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 1 comment.

File	Description
jsocket/jsocket_base.py	Adds closed-fd detection + socket recreation in connect(), hardens _send(), and tracks/reset server listening state.
jsocket/tserver.py	Improves wakeup socket fallback cleanup, adjusts accept-loop logging, and spawns workers only after successful accept/handoff.
tests/test_additional_coverage.py	Adds regression coverage for reconnect-after-close avoiding the backoff sleep path.
jsocket/_version.py	Bumps package version to 2.0.2.

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