FEATURE REQUEST:Doctor's Report - Export Health Data to PDF

### Is your feature request related to a problem?

- [x] Yes, it is related to a problem

### Describe the feature you'd like

## 🌟 Feature Description
I propose implementing a **"Doctor's Report" Generation** feature. This allows parents to export their baby's tracked data (Feeding logs, Sleep patterns, Growth stats, and Vaccination history) into a clean, professional PDF document.

This feature transforms the app from a simple daily tracker into a medical utility tool, allowing parents to easily share health summaries with pediatricians during check-ups.

## 🔍 Problem Statement
Currently, all vital data regarding the baby's health is locked inside the application's interface.
1. **Consultation Friction:** When visiting a doctor, parents have to manually scroll through days of history on their phone to answer questions like *"How has the sleep cycle been this week?"* or *"Is the baby feeding frequently?"*
2. **Data Portability:** There is no way to backup this data in a readable format or send it via email/WhatsApp to family members or caregivers.
3. **Privacy:** Handing an unlocked phone to a doctor or nurse to look at charts is not ideal for privacy.

## 🎯 Expected Outcome
The goal is to provide a one-click solution to generate a health summary.
1. **Date Range Selection:** A modal asking the user to select the duration (e.g., *Last 7 Days*, *Last 30 Days*, or *Custom Range*).
2. **PDF Generation:** The app generates a PDF containing:
* **Header:** Baby Name, Age, Weight, Date of Report.
* **Summary Table:** Average Sleep Hours, Total Feedings, Diaper Change counts.
* **Detailed Logs:** Chronological list of events for the selected period.
3. **Sharing Capabilities:** Integration with the native OS "Share Sheet" to send the PDF to Email, WhatsApp, or Save to Files.

## 📷 Screenshots and Design Ideas
**Proposed UI Workflow:**
1. **Settings/Profile Tab:** Add a new section labeled **"Data & Reports"**.
2. **Action Button:** A button labeled **"Export Doctor's Report"** with a PDF icon.
3. **Filter Modal:**
* *Title:* "Select Report Period"
* *Options:* [Last Week] [Last Month] [Custom]
* *Action:* [Generate PDF]
4. **PDF Layout:**
* Clean white background with black text (printer-friendly).
* Simple tables for data.
* A "Notes" section at the bottom for the doctor.

## 📋 Additional Context
**Technical Implementation Strategy:**
I have analyzed the requirements and recommend using standard PDF generation libraries compatible with the project's stack.
* **For PDF Generation:** We can use libraries like `jspdf` or platform-specific converters (e.g., `expo-print` if React Native) to render an HTML string into a PDF.
* **For Sharing:** Use the native sharing intent to handle the generated file.

I am highly interested in working on this feature. It adds significant value to the "Medical/Health" aspect of BabyNest. I can start by setting up the PDF generation utility function.

### Record

- [x] I agree to follow this project's Code of Conduct
- [x] I want to work on implementing this feature