Phase 07 of #1162. Splits tool-sanitization + codex-reasoning proxy spawn
out of the orchestrator:
- src/cliproxy/executor/proxy-chain-builder.ts (185 LOC):
buildProxyChain + ProxyChainContext / ProxyChainResult types.
DI escape hatch (_ToolSanitizationProxy / _CodexReasoningProxy) for
testability without refactoring the proxy classes (Bun module cache
blocks mock.module of already-loaded modules).
- 9 unit tests covering codex-only, tool-san only, both-together,
spawn failure swallowing, env propagation.
index.ts: 716 -> 665 LOC (-51). HTTPS tunnel kept inline because
tunnelPort is needed by image-analysis resolution before first-pass
buildClaudeEnvironment — folding it in would also require moving image
analysis. Two-pass buildClaudeEnvironment dance preserved exactly.
Behavior unchanged; full suite passes 1824/1824.
Refs #1162
