docs(llm-timeout): 0-as-disable 함정 명시 + HOTFIXES typo + 용어 정리

PR #162 워커 리뷰 반영.

- MEDIUM (W2) + LOW (W1): request_timeout_secs = 0 이 reqwest 의
  의미상 disable 이 아닌 instant timeout (모든 요청 즉시 실패).
  LlmCfg field rustdoc + ollama.rs module-level comment + README
  세 군데에 명시 + u64::MAX / 86400 같은 large finite 값 권장.
- NIT (W1): HOTFIXES 2026-05-25 entry 의 '답변이 인 5분' typo →
  '답변이 5분' (1자 삭제).
- NIT (W1): README + HOTFIXES 의 '확장 도그푸딩' 내부 jargon →
  '후속 도그푸딩' 으로 통일.

코드 동작 변경 없음 — doc only. cargo test request_timeout 3 PASS.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

crates/kebab-config/src/lib.rs

@@ -130,6 +130,13 @@ pub struct LlmCfg {
     /// user. Config-driven so 16-GB / CPU-only deployments using small
     /// (≤4B) models can keep the original 300s and large-model dogfood
     /// can dial it up (e.g. 1200s) without rebuilding.
+    ///
+    /// **Edge case — `0` is NOT a disable sentinel.**
+    /// `reqwest::ClientBuilder::timeout(Duration::from_secs(0))` sets a
+    /// 0-second read timeout, so every request fails *immediately* with
+    /// `error: kb-rag: ollama timeout`. To approximate "no cap", use a
+    /// large finite value (e.g. `u64::MAX` ≈ 5.8 × 10¹¹ years, or
+    /// just a generous number like `86400`).
     #[serde(default = "default_llm_request_timeout_secs")]
     pub request_timeout_secs: u64,
 }