Squash merge of feat/claude-code-native-parity into release/v3.6.5.
## Wiring
1. base.ts: CCH xxHash64 body signing for anthropic-compatible-cc-* providers,
applied after CLI fingerprint ordering so the hash covers the final bytes
sent upstream.
2. chatCore.ts: After buildClaudeCodeCompatibleRequest(), applies synchronous
parity pipeline steps:
- remapToolNamesInRequest() — TitleCase tool name mapping (14 tools)
- enforceThinkingTemperature() — temperature=1 when thinking active
- disableThinkingIfToolChoiceForced() — remove thinking on forced tool_choice
Cache-control limit enforcement intentionally omitted from chatCore because
the billing-header system block counts toward the 4-block cap and would strip
legitimate client cache markers.
3. xxhash-wasm: installed (was declared in package.json by PR but not installed).
## Test updates
- tests/unit/claude-code-parity.test.mjs: 25 new tests covering CCH signing,
fingerprint computation, tool remapping, and API constraints.
- tests/unit/cc-compatible-provider.test.mjs: fixed pre-existing assertion that
expected no cache_control on system blocks (billing header now carries ephemeral
per PR #1188 design).
Closes#1188
diegosouzapw
3b4e7b0e5f