fix(bluebubbles): isolate standalone sends from gateway lifecycle

[Cloudymap1e]

Summary

• connect temporary BlueBubbles senders in outbound-only mode without binding or unregistering the inbound webhook
• keep standalone sender connect/disconnect from mutating the live gateway's persisted PID/status record
• keep standalone fallback independent of the live adapter, avoiding duplicate and cross-event-loop retries after callers already attempted live delivery
• preserve normal gateway listener, webhook registration, and lifecycle behavior

Fixes #78424

Testing

• scripts/run_tests.sh -j 1 tests/gateway/test_bluebubbles.py -q — 22 passed
• ruff check gateway/platforms/bluebubbles.py tools/send_message_tool.py tests/gateway/test_bluebubbles.py — passed
• git diff --check — passed

Checklist

• Focused behavior-level regression coverage
• No new dependency or configuration key
• Normal inbound gateway lifecycle remains the default
• Focused diff with no unrelated changes

[alt-glitch]

This was generated by AI during triage.

Duplicate of #51763. Its send_only adapter path already avoids the standalone webhook bind and preserves the live gateway lifecycle/status state.

[Cloudymap1e]

Closing in favor of the earlier #51763, which covers the same outbound-only BlueBubbles lifecycle and standalone-send path.