test: add unit tests for event_actions, structured_events, example_util, run_config, and forwarding_artifact_service

[nuthalapativarun]

Problem / Solution

Five source files lacked unit test coverage. This PR adds test files for each:

Source file	New test file	Tests added
core/src/events/event_actions.ts	core/test/events/event_actions_test.ts	15
core/src/events/structured_events.ts	core/test/events/structured_events_test.ts	12
core/src/examples/example_util.ts	core/test/examples/example_util_test.ts	12
core/src/agents/run_config.ts	core/test/agents/run_config_test.ts	8
core/src/tools/forwarding_artifact_service.ts	core/test/tools/forwarding_artifact_service_test.ts	12

Total: 59 new tests.

Testing Plan

• Unit tests added for all five files
• All 59 new tests pass locally
• Full unit:core suite passes (1516 tests, 125 files)
• npm run lint — no new errors introduced by this PR
• npm run format — all new files formatted with prettier

Test Files  125 passed (125)
     Tests  1516 passed (1516)

Checklist

• Code follows the existing style of the project
• Tests follow the describe/it + vitest pattern used throughout core/test/
• No source files modified — test-only PR
• Lint and format pass