review: follow-ups to #48 (env default, contextvars unbind, schema tests)

[trick77]

Summary

Addresses the code-review feedback on the merged PR #48 (Splunk-friendly JSON logs):

• RIPTIDE_ENV default in openshift/collector/configmap-app.yaml flipped from "prod" to "unknown". A forgotten overlay patch now stands out in Splunk instead of silently mis-tagging records as production.
• Stale comment in openshift/collector/deployment.yaml about overridable index annotation dropped — we never set that annotation.
• access_log middleware (src/riptide_collector/main.py):
  • _SILENT_PATHS check uses rstrip("/") so /health/ (trailing slash) is also silenced.
  • clear_contextvars() replaced with unbind_contextvars(*bound) — we only unbind what we bound, preserving any contextvars set by an outer layer.
  • Added a sentinel comment on the status_code = 500 fallback so a future reader doesn't misread it as a bug.
• Field-naming convention aligned across routers:
  • noergler_event_type → event_type in routers/noergler.py.
  • run_status → status in routers/pipeline.py.
  • webhook_source already disambiguates these in Splunk panels; source-namespaced field names are no longer used.
• AGENTS.md documents the convention so the next add-a-source PR doesn't reinvent it.
• tests/test_log_schema.py (new): the schema-regression suite the unification was supposed to enable. Two layers:
  • Call-site (per router): swap the root StreamHandler's stream to an in-memory buffer (capfd/capsys don't reach handlers that captured sys.stdout before the test started), parse the JSON lines, assert required keys, outcome semantics, no Splunk-reserved leaks, accepted→deduped on replay, delivery_id even on ignored paths, request_id propagation, /health silence.
  • Processor-chain: run the prod processor list on a synthetic event_dict and assert event→msg, level→log_level, reserved-name stripping, and service/version/env stamping.

Test plan

• uv run ruff check . && uv run ruff format --check .
• uv run pyright — 0 errors
• uv run pytest — 179 passed (170 baseline + 9 new schema tests)
• On intg, confirm RIPTIDE_ENV overlay patch is in place (otherwise records will tag env=unknown)