fix(docker): Fix docker-compose stack

[ATMackay]

No description provided.

[Copilot]

Pull Request Overview

This PR migrates the application from using float64 for monetary values to using the shopspring/decimal library for more precise financial calculations, and significantly improves the Docker Compose configuration with proper service orchestration and environment variable management.

• Replaces all monetary float64 fields with decimal.Decimal for precise financial arithmetic
• Adds comprehensive Docker Compose setup with PostgreSQL and SQLite profiles, health checks, and environment variable configuration
• Refactors code structure with improved naming and reduced duplication

Reviewed Changes

Copilot reviewed 16 out of 17 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
model/items.go	Updates Item.Price field to use decimal.Decimal with appropriate validation
model/order.go	Changes Order.Price field to decimal.Decimal with database column type update
server/purchase.go	Converts price calculations to use decimal operations with float conversion for totals
server/item.go	Updates price response handling to convert decimals to float64 for API responses
promotions/promotion.go	Refactors discount calculations to use decimal arithmetic
promotions/promotion_test.go	Updates test data to use decimal.NewFromFloat for price initialization
client/client_test.go	Modifies test assertions to work with decimal price calculations
docker-compose.yml	Complete rewrite with PostgreSQL/SQLite profiles, health checks, and environment variables
cmd/run.go	Refactors flag binding with helper function and improves code organization
cmd/version.go	Renames function for consistency
cmd/cmd_test.go	Updates test to use renamed function
cmd/cmd.go	Adds environment prefix constant
Makefile	Improves DIRTY flag detection and updates Docker targets
Dockerfile	Updates Alpine base image version
go.mod	Adds shopspring/decimal dependency
docs/openapi/openapi.json/swagger.json	Updates API schema to reflect price field name change

Comments suppressed due to low confidence (1)

server/purchase.go:1

• The environment variable uses PG_HOST_PORT but should use 5432 as the container port since the application connects to the database service internally, not via the host port mapping.

package server

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