feat(backend): Implement Phase 2.7 Task 1 - Medication Management System

This commit implements the complete medication management system,
which is a critical MVP feature for Normogen.

Features Implemented:
- 7 fully functional API endpoints for medication CRUD operations
- Dose logging system (taken/skipped/missed)
- Real-time adherence calculation with configurable periods
- Multi-person support for families managing medications together
- Comprehensive security (JWT authentication, ownership verification)
- Audit logging for all operations

API Endpoints:
- POST   /api/medications          - Create medication
- GET    /api/medications          - List medications (by profile)
- GET    /api/medications/:id      - Get medication details
- PUT    /api/medications/:id      - Update medication
- DELETE /api/medications/:id      - Delete medication
- POST   /api/medications/:id/log  - Log dose
- GET    /api/medications/:id/adherence - Calculate adherence

Security:
- JWT authentication required for all endpoints
- User ownership verification on every request
- Profile ownership validation
- Audit logging for all CRUD operations

Multi-Person Support:
- Parents can manage children's medications
- Caregivers can track family members' meds
- Profile-based data isolation
- Family-focused workflow

Adherence Tracking:
- Real-time calculation: (taken / total) × 100
- Configurable time periods (default: 30 days)
- Tracks taken, missed, and skipped doses
- Actionable health insights

Files Modified:
- backend/src/handlers/medications.rs - New handler with 7 endpoints
- backend/src/handlers/mod.rs - Added medications module
- backend/src/models/medication.rs - Enhanced with repository pattern
- backend/src/main.rs - Added 7 new routes

Phase: 2.7 - Task 1 (Medication Management)
Status: Complete and production-ready
Lines of Code: ~550 lines

backend/Dockerfile.improved

@@ -0,0 +1,55 @@
+# Multi-stage Dockerfile for Normogen Backend
+# Stage 1: Build the Rust application
+FROM rust:1.93-slim as builder
+
+WORKDIR /app
+
+# Install build dependencies
+RUN apt-get update && apt-get install -y \
+    pkg-config \
+    libssl-dev \
+    && rm -rf /var/lib/apt/lists/*
+
+# Copy manifests
+COPY Cargo.toml Cargo.lock ./
+COPY src ./src
+
+# Build the application in release mode
+RUN cargo build --release
+
+# Stage 2: Runtime image
+FROM debian:bookworm-slim
+
+# Install runtime dependencies only
+RUN apt-get update && apt-get install -y \
+    ca-certificates \
+    libssl3 \
+    && rm -rf /var/lib/apt/lists/* \
+    && apt-get clean
+
+# Create a non-root user
+RUN useradd -m -u 1000 normogen
+
+WORKDIR /app
+
+# Copy the binary from builder
+COPY --from=builder /app/target/release/normogen-backend /app/normogen-backend
+
+# Change ownership
+RUN chown -R normogen:normogen /app
+
+# Switch to non-root user
+USER normogen
+
+# Expose the port
+EXPOSE 8000
+
+# Health check
+HEALTHCHECK --interval=30s --timeout=10s --start-period=5s --retries=3 \
+  CMD curl -f http://localhost:8000/health || exit 1
+
+# Set the entrypoint to ensure proper signal handling
+ENTRYPOINT ["/app/normogen-backend"]
+
+# Run with proper signal forwarding
+CMD []