fix: harden video-translate from end-to-end testing

[davidchou-heygen]

Follow-up to #43 — eight fixes found by running the skill end-to-end against real translations. Targeting Ken's PR branch directly so it lands as part of #43 when merged.

Install path

• Move skills/video-translate/ → video-translate/ to match heygen-avatar/ and heygen-video/ layout (./setup looks for skills at repo root)
• Register video-translate in setup's SKILLS array so it gets symlinked alongside the other two

Skill content

• Interactive intake — ask one question at a time, extract from first message, propose sensible defaults instead of a 4-question form
• API key resolution from ~/.heygen/config — mirrors parent SKILL.md's 3-source order (env > config file > prompt user)
• Soak-then-tight polling — 5-min silent soak, then 30s polls until terminal; never "check back in 20 min"
• Backgrounded bash polling — replaces the broken Agent subagent path (subagents can't inherit Bash approvals in Claude Code, every curl in them dies on permission denial)
• Upfront approval-count warning before launching N background polls
• Narrate-before-each-Bash rule — one sentence about why before every shell call
• Markdown-link-wrapped delivery — flag emoji header + view-online link + [Download .mp4] + [SRT] · [VTT]; stops dumping 200-char signed URLs into the terminal
• Shell hygiene section — env vars don't persist across Bash calls (inline auth load every time), zsh "no matches found" = unquoted glob, don't burn approvals on diagnostics
• Fix \$status zsh read-only collision in poll script template (rename to \$st with explanatory comment)
• Correct languages endpoint response shape: real API returns { languages: string[] }, not { data: [{ code, name }] }
• Correct dashboard URL pattern: /videos/{id} not /video-translate/{id}

Test plan

• Run ./setup from a fresh checkout — verify video-translate symlinks into ~/.claude/skills
• Submit a translation end-to-end and verify: one approval per language, no foreground polling, deliverable renders with clickable links
• Verify the language list query returns successfully on first call (no jq path error)

[davidchou-heygen]

Superseded by #46 (PR against master containing @kenchung's full v3 rewrite + my hardening commit). Closing this since it stacked on #43, which is also being superseded.