fix: render dosage result inline in calculator panel

[DeepRatAI]

Summary

Closes #16

Adds inline display of dosage calculation results directly in dosage_calculator_panel() using rx.cond(MedeXState.dosage_result). Previously, the computed dosage was only accessible through the artifact card modal ("Ver Más").

Changes

ui/medex_ui/app.py

• Added rx.cond(MedeXState.dosage_result != "", rx.box(rx.markdown(...))) block between the error display and the artifacts grid
• Result renders with rx.markdown() for proper formatting of the dosage fields
• Styled with THEME.PRIMARY_50 background and border to match the panel aesthetic

Before/After

Before	After
User clicks Calculate → sees generic artifact card title	User clicks Calculate → result (dose, frequency, max daily, warnings) shown immediately inline
Must click "Ver Más" on artifact card to see actual values	Artifact card still available for modal view, but values are visible without extra interaction

Technical Details

• MedeXState.dosage_result (str) is already populated correctly by _format_dosage_result() in state.py
• No state changes needed — only rendering was missing
• The rx.cond pattern matches Error/Loading patterns already used in the panel