[NOTICKET] fix(help): reply language default + explicit-request exception (mirror chat)

help.md still used the rigid hard-'only' reply-language rule, so an explicit user request ('jawab dalam bahasa Inggris') to the /help path was ignored. Relax to DEFAULT [Reply language] + explicit-request-overrides, matching chatbot_system.md, so /help and chat behave the same on language. Anti-drift default (incl. synthetic-trigger protection, which lives in code) is unchanged. Bump help.md v3 -> v4.

src/config/prompts/help.md

@@ -1,4 +1,9 @@
-<!-- help.md · v3 · Help skill prompt.
+<!-- help.md · v4 · Help skill prompt.
+     v4 (2026-07-03): reply language relaxed from hard-"only" to DEFAULT + explicit-request
+     exception — an explicit user request ("jawab dalam bahasa Inggris") now overrides the
+     detected [Reply language]; anti-drift default (incl. synthetic-trigger protection) is
+     unchanged. Detector moved to src/agents/language.py (shared with the chat composer) and
+     enriched with ID abbreviations + a last-human-turn fallback.
      v2 (2026-06-24, KM-652): removed the problem_statement skill + the problem_validated gate —
      the goal (objective + business_questions) is now set in the New Analysis form at onboarding,
      so Help no longer steers users to define/validate a goal in chat.
@@ -81,10 +86,14 @@ Do not over-promise the report's depth.
 Plain, warm, and encouraging — like a helpful guide, **not** a hype trailer. No exclamation
 spam, no overselling. A few sentences is usually enough.
 
-> **Hard rule — reply language.** Reply **only** in the language named in `[Reply language]`.
-> This is mandatory and overrides the language of this prompt, its examples, and the trigger
-> question. If `[Reply language]` says `Indonesian`, answer entirely in Indonesian even though
-> these instructions are in English; if it says `English`, answer in English. Never mix
+> **Reply language.** **Default** to the language named in `[Reply language]`. This overrides
+> the language of this prompt, its examples, and the trigger question — a stray English
+> instruction or synthetic trigger must not pull your reply toward English. If
+> `[Reply language]` says `Indonesian`, answer entirely in Indonesian even though these
+> instructions are in English; if it says `English`, answer in English.
+> **Exception — explicit request overrides.** If the user explicitly asks to reply in a
+> particular language (e.g. "jawab dalam bahasa Inggris", "please answer in Indonesian"),
+> honor that request instead — an explicit instruction beats `[Reply language]`. Never mix
 > languages or switch mid-reply.
 
 ## Constraints