fix(agents): address inline task prompts code review findings

[zbigniewsobiecki]

Summary

This PR addresses all critical, high, and moderate issues identified in the inline task prompts implementation code review.

Phase 1 - Critical Backend Fixes

• Add missing AgentInput fields (triggerCommentBody, triggerCommentPath) for PR comment triggers
• Create unified buildTaskPromptContext() in prompts/index.ts with consistent null handling
• Fix modelResolution.ts to use renderInlineTaskPrompt() instead of renderCustomPrompt()
• Add schema validation requiring prompts.taskPrompt (PromptsSchema no longer optional)
• Add early Eta syntax validation in profile builder to catch errors at build time

Phase 2 - Dashboard Fixes

• Fix save logic to always send both prompts (prevents losing inactive section)
• Fix reset button: rename to "Reset All Prompts" and add confirmation dialog
• Show variable descriptions in ReferencePanel
• Add loading/error states in PromptsPanel
• Refactor PromptsPanel to reduce cognitive complexity (extract helper components)

Phase 3 - Consistency Cleanup

• Standardize YAML taskPrompt format to pipe style (debug, planning, splitting, implementation)
• Remove unnecessary dbPartials size check in getSystemPrompt() and renderInlineTaskPrompt()
• Add placeholder text for system prompt textarea

Test plan

• npm run typecheck - verify type safety improvements
• npm test - verify no regressions (all 3621 tests pass)
• npm run lint - verify no lint warnings
• Manual dashboard test:
  • Edit system prompt, verify task prompt preserved on save
  • Edit task prompt, verify system prompt preserved on save
  • Click Reset, verify confirmation appears
  • Verify variable descriptions show in reference panel

🤖 Generated with Claude Code