feat: 报告输出语言新增韩语支持 (Korean report language, ko) (#1614) (#1844)

* feat(i18n): add Korean to report language label maps

Extend the report language layer with a third code `ko` so reports can
render deterministic labels in Korean. Adds `ko` to the supported list,
aliases (korean/kr/ko-kr), every translation map, the full report label
set, sentiment bands, the config registry enum and `.env.example`.
`zh`/`en` behavior is unchanged and unknown languages still fall back to
the default. Prompt and Web surfaces follow in later changes.

Refs #1614

* feat(i18n): emit Korean output directives in analysis prompts

Make the analysis and market-review prompts produce Korean output when
REPORT_LANGUAGE=ko. The decision agent now appends a Korean
output-language directive (JSON keys and decision_type enum unchanged),
and the market-review prompt reuses the English structural scaffolding
while instructing the model to write the shell, headings and conclusion
in Korean. Market-phase and context-pack prompt sections route ko to the
English structural base. The market-review payload keeps the truthful
language code via a dedicated output-language helper, leaving zh/en
behavior unchanged.

Refs #1614

* fix(i18n): localize phase and market-context guardrails for Korean

Route Korean reports through the English structural scaffolding for
market-phase and market-context prompt sections, and add Korean output,
detection markers, negations and recap patterns to the phase-decision and
daily-market-context guardrails so they operate on Korean model output.
Confidence and operation labels now flow through the shared localize
helpers. zh/en behavior is unchanged.

Refs #1614

* feat(i18n): localize Korean fallback output across analysis pipeline

Add Korean output to the deterministic strings emitted outside the LLM:
per-stock and executor output-language directives, no-API-key / backend
/ parse error fallbacks, hold-watch advice and reasons, market-review
titles and summaries, and history and notification report labels. Fund
flow, trend and confidence values now flow through the shared localize
helpers, and language-keyed advice tables no longer raise KeyError for a
third language. Structural prompt sections route ko to the English
scaffolding. zh/en output is unchanged.

Refs #1614

* feat(web): add Korean report language rendering

Extend the Web ReportLanguage type with ko and add Korean copy to the
report detail surfaces: report text, sentiment labels, market-phase
labels, analysis-context summary, market-review view, diagnostics and
news source. Run-flow chrome that is keyed by UI language falls back to
English for ko. The report-language selector is driven by the backend
config schema, so Korean appears automatically. zh/en rendering is
unchanged.

Refs #1614

* docs(i18n): document Korean report language support

Note that REPORT_LANGUAGE accepts ko in the bilingual guides and the
analyze / market-review request-language parameters, and add a
CHANGELOG entry for Korean report output.

Refs #1614

* fix(i18n): canonicalize Korean values and accept ko in API schemas

Add Korean aliases to the operation-advice, trend, confidence, chip and
bias canonical maps so Korean model output (매수/매도/보유/관망 etc.)
resolves to the correct decision_type and signal level instead of
falling back to hold or a score-band signal. Accept ko in the
analyze, market-review and decision-signal request schemas (and the
static API spec) so the typed client and backend agree and per-request
Korean analysis is not rejected with 422.

Refs #1614

.env.example

@@ -668,7 +668,7 @@ AGENT_SKILLS=
 # 报告类型：simple(精简)、full(完整)、brief(3-5句概括)
 # Docker环境下如果推送内容不完整，可以设置为 full
 # REPORT_TYPE=simple
-# 报告输出语言：zh(中文，默认) / en(英文)
+# 报告输出语言：zh(中文，默认) / en(英文) / ko(韩文)
 # REPORT_LANGUAGE=zh
 # 仅分析结果摘要：设为 true 时只推送汇总，不含个股详情
 # REPORT_SUMMARY_ONLY=false