feat: add Indonesian (id) locale

[ardha27]

What

Adds Bahasa Indonesia as a supported language in MiroFish's i18n registry:

• locales/id.json — full translation of 629 keys across 17 sections (common, meta, nav, home, main, step1–step5, graph, history, api, progress, log, report, console)
• locales/languages.json — register the id entry with label and llmInstruction

Why

The current i18n registry has 7 languages (zh, en, es, fr, pt, ru, de) but is missing Indonesian despite:

• Indonesian being the 4th most-spoken language in the world (~270M speakers)
• MiroFish's apparent target use cases (policy rehearsal, social simulation, economic prediction) being directly relevant to Indonesian ministries and think tanks
• Real-world usage: a Purbaya/USD-IDR 15,000 simulation in Bahasa Indonesia context is exactly the kind of scenario the framework is built for, and currently has to fall back to English

How to use

After this lands, Indonesian users can switch via:

• Frontend: language picker in the UI (drops in automatically once the locale file is loaded by import.meta.glob in frontend/src/i18n/index.js)
• API: Accept-Language: id header on backend calls — the get_locale() route in backend/app/utils/locale.py picks it up automatically
• LLM behavior: get_language_instruction() will return "Silakan jawab dalam bahasa Indonesia.", anchoring the LLM to respond in Bahasa Indonesia across ontology generation, simulation config, persona profiles, and reports

Translation quality

Generated with deepseek-chat from en.json. Validated against the upstream English file:

• 629/629 keys preserved (same nesting, same types)
• 0 values with English stopword ratio > 30% (i.e. no mostly-English text accidentally left in the Indonesian file)
• Technical terms preserved: MiroFish, API, LLM, PDF, Zep, placeholders like {title} / {conflictCount}

Spot check:

Key	English	Indonesian
common.confirm	Confirm	Konfirmasi
common.cancel	Cancel	Batal
common.retry	Retry	Coba Lagi
meta.title	MiroFish - Predict Anything	MiroFish - Prediksi Segalanya
step2.profileModalAge	Apparent Age	Usia Tampak
step5.chatEmptyAgent	Chat with simulated individuals to understand their perspectives	Chat dengan individu yang disimulasikan untuk memahami perspektif mereka
report.sectionConflictDowngrade	Section {title}: {conflictCount} consecutive conflicts, downgrading to truncate and execute first tool call	Bagian {title}: {conflictCount} konflik berturut-turut, menurunkan ke pemotongan dan eksekusi panggilan alat pertama

Files

• locales/id.json (new, 39,648 bytes, 629 keys)
• locales/languages.json (modified, +4 lines for id entry)

Risk

Zero. Additive change only — no existing behavior modified. Languages already not selected by users continue to behave identically. The 4-line addition to languages.json follows the exact pattern of the existing 7 entries.

Checklist

• All 629 keys present and translated
• No suspicious English text in Indonesian file
• Technical terms (brand names, placeholders) preserved
• languages.json registration follows existing pattern
• Follows upstream's i18n conventions (no code changes required for frontend/backend to pick it up)