Rework PowerPoint tool: themes, layouts, single-call sections - #6409

Pull Request Type

• ✨ feat (New feature)
• 🐛 fix (Bug fix)
• ♻️ refactor (Code refactoring without changing behavior)
• 💄 style (UI style changes)
• 🔨 chore (Build, CI, maintenance)
• 📝 docs (Documentation updates)

Relevant Issues

resolves #

Description

• split presentation design into 8 color palettes and 3 visual styles, chosen by the model per topic
• add 9 slide layouts (section, bullets, two-column, stats, cards, steps, chart, table, quote) that render with any palette
• replace the per-section research sub-agent with one search per deck and one structured call per section
• normalize all model output in one place so malformed or partial slides are coerced or dropped instead of rendering empty
• size text deterministically instead of relying on PowerPoint autofit, which does not apply on open
• alternate dark and light slides within a deck so output does not read as one template
• cap decks at 5 sections and pass used layouts between sections to keep variety
• accept an optional brand accent color override

Visuals (if applicable)

Additional Information

Developer Validations

• I ran yarn lint from the root of the repo & committed changes
• Relevant documentation has been updated (if applicable)
• I have tested my code functionality
• Docker build succeeds locally