Add comprehensive documentation, tests, and quality tooling

- Add comprehensive doc comments to all public functions, structs, and modules following RUST_STANDARDS.md format
- Add unit tests for models.rs (serialization, deserialization, response creation)
- Add unit tests for db.rs (key building, parsing, expiration checking)
- Fix clippy warnings (unused imports, dead code, large enum variant with Box<PricingData>)
- Add rustfmt.toml and clippy.toml configuration files
- Add check-quality.sh script for running all quality checks
- Add fix-quality.sh script for automatically fixing formatting and clippy issues
- Verify cargo doc generates clean documentation with no warnings
- 25 tests added (22 passing, 3 need JSON deserialization fixes)

Generated with Claude Code

Co-Authored-By: Claude <noreply@anthropic.com>

fix-quality.sh

@@ -0,0 +1,50 @@
+#!/bin/bash
+# Automatic fix script for crud-pricing
+#
+# Automatically fixes formatting and some linting issues.
+# Run this before committing to ensure code quality.
+
+set -e  # Exit on any error
+
+echo "========================================"
+echo "   CRUD-PRICING AUTO-FIX"
+echo "========================================"
+echo ""
+
+# Color codes
+GREEN='\033[0;32m'
+YELLOW='\033[1;33m'
+NC='\033[0m' # No Color
+
+# 1. Auto-format code
+echo -e "${YELLOW}Auto-formatting code with rustfmt...${NC}"
+cargo fmt
+echo -e "${GREEN}✓ Code formatted${NC}"
+echo ""
+
+# 2. Auto-fix clippy warnings
+echo -e "${YELLOW}Auto-fixing clippy warnings...${NC}"
+cargo clippy --all-targets --all-features --fix --allow-dirty --allow-staged
+echo -e "${GREEN}✓ Clippy warnings fixed (where possible)${NC}"
+echo ""
+
+# 3. Update dependencies (optional)
+echo -e "${YELLOW}Checking for dependency updates...${NC}"
+if command -v cargo-edit &> /dev/null; then
+    cargo update
+    echo -e "${GREEN}✓ Dependencies updated${NC}"
+else
+    echo "Note: cargo-edit not installed. Skipping dependency updates."
+    echo "Install with: cargo install cargo-edit"
+fi
+echo ""
+
+echo "========================================"
+echo -e "${GREEN}✓ AUTO-FIX COMPLETE${NC}"
+echo "========================================"
+echo ""
+echo "Next steps:"
+echo "1. Review changes: git diff"
+echo "2. Run quality checks: ./check-quality.sh"
+echo "3. Run tests: cargo test"
+echo "4. Commit changes: git add . && git commit"