fix(taskctl): upgrade adversarial-pipeline and developer-pipeline prompts

[randomm]

Summary

Upgrades both pipeline agent prompts in agent.ts based on failures observed in live pipeline runs and the richer reference prompts in lievo/prompts/.

adversarial-pipeline

• Test directory: Must run bun test and bun run typecheck from packages/opencode, not project root (fixes "do-not-run-tests-from-root" error)
• Scope enforcement: Out-of-scope additions flagged as ISSUES_FOUND (HIGH/MEDIUM)
• Cross-platform: Hardcoded /tmp/ or /var/folders in test assertions flagged as CRITICAL
• Explicit APPROVED criteria: All 6 conditions must be true (replaces vague current criteria)
• Attack vectors checklist: 7 structured review dimensions
• colgrep/vipune/context7: MUST-use instructions with correct syntax

developer-pipeline

• colgrep: MUST search before implementing to prevent duplication
• vipune: Search for prior decisions at startup, store learnings after
• context7: MANDATORY before any library API usage
• Test directory: Explicit packages/opencode instruction

Fixes #269