DeepSeek's native API returns prompt_tokens/completion_tokens but not
`usage.cost`. OpenRouter returns both. Result: with DeepSeek-direct as
primary (current default), every LogResult.cost_usd was None — and
every downstream cost ledger row (AICall, StrategicLog,
IndicatorSummary, translation tables) stored None instead of the real
spend.
Added a per-model rate table and fallback computation in _call_provider:
when the upstream omits cost, multiply tokens by the table rates. If the
upstream DOES return cost, keep it (authoritative). Falls back to None
if both the upstream and the table miss.
deepseek-v4-flash rates: \$0.07/M input, \$0.28/M output (per DeepSeek).
Giorgio Gilestro
7348055d72