DeepSeek models had no provider-policy-api.ts, so materializeRuntimeConfig
filled contextWindow with DEFAULT_CONTEXT_TOKENS (200k) and cost with zeros
for all DeepSeek models. This caused premature session compaction at ~125k
instead of using the full 1M window, and zero-cost display for v4 models.
Add a normalizeConfig surface that hydrates missing contextWindow, maxTokens,
and cost from the bundled DeepSeek model catalog for matching model ids.
Explicit user overrides are preserved.
Fixes#74245
