Drop all hard-coded model-name lookup tables that hardcoded specific
model names and prices:
- infer_context_length: remove GPT-4o/o1/Claude/etc. fallback table
- infer_max_output: remove GPT-4o/o1/etc. output token limits
- infer_pricing_fallback: remove entire hardcoded pricing table
- infer_capability_list: derive from architecture.modality only,
no longer uses model name strings
Also fix stats: if upsert_version fails, skip counting and continue
rather than counting model but not version (which caused
versions_created=0 while pricing_created>0 inconsistency).
- Add `start_sync_task()` in agent/sync.rs: spawns a background task
that syncs immediately on app startup, then every 10 minutes.
- `sync_once()` performs a single pass; errors are logged and swallowed
so the periodic task never stops.
- Remove authentication requirement from OpenRouter API (no API key needed).
- Call `service.start_sync_task()` from main.rs after AppService init.
- Also update the existing `sync_upstream_models` (HTTP API) to remove
the now-unnecessary API key requirement for consistency.
