DeepSeek V4-Flash news enrichment: LLM sentiment, surprise direction, summary

Three display/warning-only upgrades to the news engine, all behind the
existing keyword path as fallback — signals are never gated on LLM
output (event_risk_caps_signals / sentiment_affects_signals stay False
per the 2026-07 audit; backtester use_news=False untouched):

- Headline sentiment: one batched call per 600s cache window (capped at
  25 new headlines, sha1-cached so repeats are never re-sent) overrides
  the keyword scores per currency with the gold-inverse doctrine encoded
  in the prompt.
- Release surprises: get_event_risk_level's description now says which
  way the print pulls GOLD ("— gold bearish: strong jobs lift yields"),
  fixing the documented numeric-only gap; risk level and windows
  unchanged.
- Market summary: 1-2 sentence macro blurb on SignalReport.news_summary,
  rendered in Telegram alerts (📰) and the CLI (🧠).

New llm_client.py: requests-only OpenAI-compatible client (no SDK), one
attempt per call, UTC-day request cap, singleton so the cap survives
per-scan NewsEngine reconstruction. Config: deepseek block in
config.json + DEEPSEEK_API_KEY env; absent key = fully inert.

Live-measured API behavior baked in: V4-Flash is a hybrid thinking model
— requests send thinking:disabled (reasoning otherwise blew the timeout
and could exhaust max_tokens before the answer); prompts are static
module constants so DeepSeek's prefix cache prices repeat calls at the
cache-hit rate; scores use compact [s, xau] pairs; timeout 12s.

Tests 273 → 286 (new Module 19 + deepseek config tests).

Claude-Session: https://claude.ai/code/session_01Nsd8HcrV67GbCZXxZEn1Ma

docs/user_guide.html

@@ -69,6 +69,7 @@
 <tr><td><b>Score / confidence</b></td><td>The regime-weighted composite of all nine indicators. Bigger absolute score = stronger consensus.</td></tr>
 <tr><td><b>MTF aligned</b></td><td>The two confirmation timeframes agree with the trade direction. Signals without alignment are filtered out on M5.</td></tr>
 <tr><td><b>Warnings ⚠️</b></td><td>Context, not veto. Backtesting shows warned trades perform about the same — strong momentum often triggers warnings.</td></tr>
+<tr><td><b>Market context 📰</b></td><td>An AI-written one-liner summarizing today's macro backdrop (headlines + high-impact releases) and its likely pull on gold. Informational only — it never blocks or grades a signal.</td></tr>
 <tr><td><b>SL / TP1 / RR</b></td><td>Stop loss sits behind the nearest swing level with an ATR buffer. TP1 is the nearest opposing level. <b>1R</b> = the entry-to-SL distance = the amount you risk.</td></tr>
 <tr><td><b>Trail plan 🔄</b></td><td>The real exit. Once price moves +0.6R in your favor (+0.8R for pullback setups), move the stop to trail 0.75R behind the best price and update it at each candle close. <b>TP1 is advisory — let winners run.</b></td></tr>
 </table>