fix: use mutable output buffer

[alexleensar]

Problem

• Outbound data is accumulated in immutable bytes. Appending data and retaining the unsent portion repeatedly copies queued bytes, increasing CPU cost as the backlog grows.
• Marti debug logging lacks useful routing context.

Unaddressed

Unbounded queue growth. This is a preexisting issue that can lead to a memory leak. Will fix in another PR.

Solution

• Queue serialized event and management payloads in an unbounded OutputBuffer backed by a deque. It uses memoryview for a single chunk, combines up to 4,096 bytes of small chunks per socket write, and removes only bytes accepted by the socket.
• Disconnect clients when a nonempty socket write makes no progress.
• Log only the Marti UID, source callsign, and destinations.
• Add tests for ordering, batching, partial and blocked writes, appends between partial writes, zero-progress writes, the existing write-size limit, immutable queued data, and management responses.

Testing

• All 28 unit tests pass.
• Will deploy to corp for further testing before PR into source repo

[brady-saronic]

Whoop Whoop! Good work @alexleensar !

[Copilot]

Pull request overview

This PR improves outbound socket transmission efficiency by replacing immutable bytes concatenation with a dedicated mutable output queue (OutputBuffer), and enhances Marti routing debug logs with more actionable context.

Changes:

• Introduces OutputBuffer (deque-backed) and migrates socket TX paths to queue/appends + partial-write removal.
• Updates Marti routing debug logging to include event UID, source callsign, and destinations.
• Adds unit tests covering ordering, batching, partial/blocked writes, and zero-progress disconnect behavior for both TAK and mgmt sockets.

Reviewed changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
tests/test_takclient.py	Adds unit tests for OutputBuffer immutability enforcement and socket TX ordering/batching/partial-write behaviors.
tests/test_mgmt.py	Adds unit test ensuring management responses are transmitted in-order via the updated buffering approach.
taky/cot/router.py	Improves Marti debug logging with UID/source/destinations context while preserving routing behavior.
taky/cot/mgmt.py	Switches management response buffering from bytes += ... to OutputBuffer.append(...).
taky/cot/client.py	Implements OutputBuffer and migrates SocketClient/SocketTAKClient TX buffering to avoid repeated bytes copying.

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