Add response envelope middleware to standardize JSON responses as
`{code,data,message}` with consistent business codes across endpoints.
Update Swagger annotations and tests to reflect the new response shape.
BREAKING CHANGE: API responses are now wrapped in a response envelope; clients must read payloads from `data` and handle `code`/`message` fields.
Change the traffic chart API response from bucket-based to series-based
to better support frontend visualization libraries. The new format
provides a shared X-axis and aligned data arrays for each model series.
- Replace `buckets` with `x` and `series` in response
- Implement data alignment and zero-filling for time slots
- Update Swagger documentation including pending definitions
BREAKING CHANGE: The `GET /admin/logs/stats/traffic-chart` response
schema has changed. `buckets` and `models` fields are removed.
Add TestTrafficChart_MinuteGranularityValidation to verify input
parameters including granularity, time range limits, and top_n
constraints. Include skipped placeholders for PostgreSQL-specific
aggregation tests.
Add group_by parameter to /admin/logs/stats endpoint supporting:
- group_by=model: aggregate stats per model with avg latency
- group_by=day: daily aggregation with token counts
- group_by=month: monthly aggregation with token counts
Also include request_body field in admin ListLogs response for
full visibility into logged requests.
