fix(#100,#101,#102): cwd fallback + cascade timeout invalidation + kimi dialect (v2.0.38)

#100 (yunduobaba) — opus refused to read Windows path because the
user's claudecode didn't emit a canonical <env> block, so cwd
extraction got nothing and cascade's built-in /tmp/windsurf-workspace
prior won. Added bare-path fallback in extractCallerEnvironment:
when canonical extractors miss, scan the FIRST user message head
for a leading absolute path (Windows / Unix / tilde). Conservative
guards (first non-trivial token only, file-extension reject) avoid
mis-attributing target paths as cwd. yunduobaba's Chinese-glued path
"C:\Users\renfei\...分析下这个项目" now lifts cleanly.

#101 (nalayahfowlkest-ship-it) — claude-opus-4.6-thinking
"context deadline exceeded" mid-stream left the cascade trajectory
half-broken, but proxy restored the entry to the reuse pool because
reuseEntryDead was only set on explicit "cascade not_found" errors.
Next request reused the broken trajectory and the model only saw
the trailing tool_result. Fix: stream + non-stream catch blocks now
also invalidate on timeout patterns (context deadline / context
cancellation / Client.Timeout). Static-analysis regression test
locks both code paths.

#102 (cookire) — kimi-k2-6 hit cascade's "The model produced an
invalid tool call". Cascade upstream's per-model parser only accepts
the kimi_k2 vLLM dialect for the original kimi-k2 / kimi-k2-thinking
SKUs; newer SKUs (kimi-k2.5, kimi-k2-6) need openai_json_xml.
Tightened pickToolDialect accordingly.

Tests: 403 -> 418 (+15: #100 fallback +9, #101 invalidation +4,
#102 dialect +2).