feat: bidirectional StorageController communication with finalize ack

[vringar]

Summary

• Add send_to_writer() to socket_interface.py for sending messages on asyncio StreamWriters
• Add ClientSocket.receive() for receiving messages on an existing connection
• StorageController sends a finalize_ack back on the StreamWriter after processing a finalize, but only when the client sets want_ack: True
• Add DataSocket.finalize_visit_id_with_ack() that sends with want_ack and waits for the ack (with timeout fallback)
• TaskManager uses the ack-aware finalize, confirming data is processed before proceeding
• Handler catches OSError alongside IncompleteReadError to handle transport poisoning from failed writes

Acks are opt-in (want_ack flag) because writing to a closed connection poisons the shared asyncio transport, preventing reads of remaining buffered messages. Only finalize_visit_id_with_ack sets this flag; fire-and-forget callers (extension, tests) are unaffected.

Stacked on #1128.

[codecov]

Codecov Report

❌ Patch coverage is 13.33333% with 39 lines in your changes missing coverage. Please review.
✅ Project coverage is 39.10%. Comparing base (8a2744c) to head (2bc92b9).

Files with missing lines	Patch %	Lines
openwpm/socket_interface.py	10.71%	25 Missing ⚠️
openwpm/storage/storage_controller.py	18.75%	13 Missing ⚠️
openwpm/task_manager.py	0.00%	1 Missing ⚠️

Additional details and impacted files

@@                         Coverage Diff                          @@
##           refactor/event-driven-completion    #1129      +/-   ##
====================================================================
+ Coverage                             35.25%   39.10%   +3.85%     
====================================================================
  Files                                    39       39              
  Lines                                  3617     3657      +40     
====================================================================
+ Hits                                   1275     1430     +155     
+ Misses                                 2342     2227     -115     

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