fix(pixel-teams): handle split multibyte utf8 sequences in sse stream decoding

[Vishaaallll]

Why this matters

In ods/extensions/services/dashboard-api/routers/pixel_teams.py, the _run coroutine decoded SSE chunks from response.body_iterator using buffered += chunk.decode("utf-8") if isinstance(chunk, bytes) else chunk. When a multi-byte UTF-8 character (such as emoji, symbols, or localized characters) is split across network TCP or chunk boundaries by the upstream inference stream, calling chunk.decode("utf-8") on an incomplete byte slice raises an unhandled UnicodeDecodeError, terminating the team worker task abruptly.

This surgical fix introduces Python's standard codecs.getincrementaldecoder("utf-8")() to buffer incomplete multi-byte sequences across chunk boundaries before appending decoded text to the line buffer.

Validation

• Baseline reproduction: verified that direct .decode("utf-8") on split chunk b'\xf0\x9f' raises UnicodeDecodeError.
• Post-fix behavior: incremental decoder buffers partial code units, decoding full characters across chunk boundaries without error.
• Telemetry: pixel-teams suite: 2 passed. New-test syntax and diff checks pass; new regression wired into Linux CI.

Overlap check

Inspected live open/closed PRs. PR #5695 touched chat cancel; PR #5689 touched team history files. Zero overlap with SSE streaming chunk decoding in pixel_teams.py.

Risk / AI disclosure

AI-assisted investigation, patch, and regression tests. Uses Python's standard incremental decoder without changing downstream SSE parsing contracts. Independent review remains a gate.

Follow-up integration evidence

Composed locally with public-beta at 4fa6ad170 without conflicts. Unit and CI checks pass.

[Lightheartdevs]

Thanks for this contribution. public-beta was promoted into main on 2026-09-24 and no longer receives changes, so we're closing pull requests that target it. This isn't a judgment on the change itself. If it's still needed, please rebase onto main and open a focused PR. See #7253 for details and the contribution policy.