Fix Cloud Browser trace agent type formatting

[xTRam1]

Summary

• emit string agent_type labels for built-in Pyodide window.agent() trace events
• make narada-core trace parsing tolerate historical numeric agent_type values
• add Cloud Browser trace tests covering built-in and nested child action traces
• bump package versions so the fix can be published and consumed by frontend/Pyodide runtime

Why

Deep Cloud Browser nested APA trace runs can fail when normal window.agent() trace events carry numeric enum values such as 2, while the trace parser expects strings. The E2E harness captured this as a real product failure in the deep Cloud Browser lane.

Validation

• uv run pytest packages/narada-pyodide/tests/test_cloud_browser.py packages/narada/tests/test_input_variables.py -q
• uv run ruff check packages/narada-core/src/narada_core/tracing/model.py packages/narada-pyodide/src/narada/window.py packages/narada-pyodide/tests/test_cloud_browser.py
• python -m py_compile packages/narada-core/src/narada_core/tracing/model.py packages/narada-pyodide/src/narada/window.py packages/narada-pyodide/tests/test_cloud_browser.py
• git diff --check

[zizhengtai]

Probably easier to redo this PR because of the merge conflicts