fix(logging): replace stdlib-style exc_info kwargs with loguru opt(exception=)

Loguru has no exc_info kwarg: extra kwargs are str.format() arguments, so
logger.error(f"...{e}", exc_info=True) forces .format() on the rendered
message — any error text containing braces (e.g. a JSON error body) raises
KeyError FROM the log call itself, escaping the surrounding except block and
killing the caller (observed: whole agent turns dying in benchmark runs).
The intended traceback was also never logged, since exc_info is not a loguru
feature.

Batch fix of all 143 sites across 11 files:
  logger.X(msg, exc_info=True) -> logger.opt(exception=True).X(msg)
  (one exc_info=exc site -> opt(exception=exc))
Messages are byte-identical; with the kwarg gone loguru never calls
.format(), so brace-containing f-string messages are inert.

Verified: AST post-conditions per file, py_compile, import smoke of all
modules, behavioral equivalence of the 3 patterns, full unit suite (1549
passed) with a failure set identical to the pristine tree (22 pre-existing,
zero regressions).

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

Also add pixel-agents to the README acknowledgements.

README.md

@@ -786,4 +786,5 @@ OpenOPC is built with gratitude for several open-source projects that helped sha
 - [BloopAI/vibe-kanban](https://github.com/BloopAI/vibe-kanban) for inspiration around kanban-centered agent work management and task visibility.
 - [msitarzewski/agency-agents](https://github.com/msitarzewski/agency-agents) for the talent-template foundation. All talent templates included in this repository are imported from `agency-agents`.
 - [HKUDS/nanobot](https://github.com/HKUDS/nanobot) for inspiration around skill-oriented agent design and `SKILL.md`-style organization.
+- [pixel-agents-hq/pixel-agents](https://github.com/pixel-agents-hq/pixel-agents) for inspiration around the animated pixel-art office visualization of agent activity.