chore: add github workflow & golang linting

[perber]

No description provided.

[Copilot]

Pull Request Overview

This pull request introduces a CI workflow for the project, including Go linting and test coverage reporting.

• Added a GitHub Actions configuration file for continuous integration
• Defined two jobs: one for linting with golangci-lint and one for running tests with coverage reporting

Files not reviewed (1)

• .golangci-lint: Language not supported

[Copilot]

Pull Request Overview

This PR adds a GitHub workflow for backend CI including Go linting and test coverage, and improves error handling across various test and service files.

• Improved error checking and handling in multipart file writes and JSON unmarshalling in HTTP tests
• Added error handling for page creation, file writes, and random byte generation in core services
• Introduced a new GitHub Actions workflow for CI and linting

Reviewed Changes

Copilot reviewed 6 out of 7 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
internal/http/router_test.go	Added error checks for multipart file writes and JSON unmarshalling in tests
internal/core/tree/tree_service_test.go	Enhanced error handling for page creation and file writes in tests
internal/core/tree/page_store.go	Refactored variable declarations in MovePage for clarity and safety
internal/core/auth/auth_service.go	Introduced error checks for rand.Read in token generation
internal/core/assets/assets_service_test.go	Added error handling for directory and file operations in asset tests
.github/workflows/backend.yml	Added new CI workflow for Go linting, testing, and coverage reporting

Files not reviewed (1)

• .golangci-lint: Language not supported

Comments suppressed due to low confidence (1)

internal/core/auth/auth_service.go:99

• Returning an empty string when rand.Read fails may lead to silent token generation issues. Consider propagating the error or handling the failure more explicitly to avoid potential security concerns.

if (_, err := rand.Read(b); err != nil) {