i18n: translate the interview modes (plan/practice/debrief) to Indonesian

**Time:** ~30–45 min · **Difficulty:** Beginner · **Native Indonesian speaker** career-ops already ships Indonesian (`modes/id/`), but not the three interview-prep modes (plan / practice / debrief). This adds them, so Indonesian-speaking job-seekers get interview prep in their own language instead of falling back to English. ### What to do 1. Create `modes/id/interview/` and translate the three files from the English source: `modes/interview/plan.md`, `modes/interview/practice.md`, `modes/interview/debrief.md`. 2. Keep every technical token **unchanged**: file paths, `{slug}` templates, the STAR+R structure, code spans, enums. Translate only the human-facing prose. 3. Keep the `##` section headers in **English**. That is the convention the existing translated interview modes follow, and it keeps the structure parseable across locales. 4. Register the new directory in SYSTEM_PATHS: one line in `update-system.mjs`, right next to the existing `'modes/id/',` entry, mirroring how `'modes/es/interview/',` is registered. ### Acceptance - `modes/id/interview/{plan,practice,debrief}.md` exist, in faithful native Indonesian. - Technical tokens byte-identical to the English source. - `node validate-system-paths-coverage.mjs` passes (the new directory is registered). ### Pattern to mirror Copy the shape of **`modes/es/interview/`** exactly: same files, same anchors, same frontmatter. The existing `modes/id/` files (`lowongan.md`, `melamar.md`) show the tone this locale already uses. *Reserved for a first-time contributor. @achievagemilang asked for this one in #1544 and it is theirs.*