CCM: Fix 1M context detection - use prefix match for versioned
beta strings (e.g. "context-1m-2025-08-07") and include cache
tokens in the 200K threshold check per Anthropic billing docs.
OCM: Add GPT-5.4 family pricing (standard/priority/flex) with
extended context (>272K) premium pricing support. Add context
window tracking to usage combinations, mirroring CCM's pattern.
Update normalizeGPT5Model defaults to latest known models.
When clients (e.g. Node.js Anthropic SDK) explicitly set Accept-Encoding: gzip,
Go's http.Transport does not transparently decompress the response body, because
it only does so when it added the header itself. This causes CCM's json.Unmarshal
to receive raw gzip bytes, silently failing to parse usage data and leaving the
usage counter unchanged.
Fix: remove Accept-Encoding from the outgoing proxy request. Transport adds it
automatically and transparently decompresses response.Body before CCM reads it.
Wire compression (CCM→Anthropic) is preserved — Transport still negotiates gzip.
Only CCM→localhost path is affected; compression on loopback has no practical
benefit.
