feat(config): add .shopware-project.local.yml override support

[Soner (shyim)]

Summary

• Adds support for .shopware-project.local.yml files that are automatically merged on top of .shopware-project.yml, similar to how Docker Compose handles compose.override.yaml
• Supports !reset YAML tag to clear fields (e.g., cleanup_paths: !reset [] empties the list instead of appending)
• Supports !override YAML tag to fully replace fields instead of deep-merging (e.g., dump: !override { nodata: [cart] } replaces the entire dump section)

Merge semantics

Type	Default	!reset	!override
Maps	Deep merge	Removes field	Full replacement
Slices	Append	Clears / sets new values only	Full replacement
Scalars	Override wins	Removes field	Same as default

Example

# .shopware-project.yml (committed)
url: https://prod.example.com
build:
  cleanup_paths:
    - var/cache
    - var/log

# .shopware-project.local.yml (gitignored, personal)
url: https://local.example.com
build:
  cleanup_paths: !reset
    - my/custom/path

Test plan

• Unit tests for localConfigFileName derivation
• Scalar override (local value wins, base preserved when absent)
• Slice append by default
• !reset clears slices to empty
• !reset with new values replaces list entirely
• !override replaces entire map section
• !reset on nested fields preserves siblings
• No local file — behaves identically to before
• Works alongside include: mechanism
• Empty local file is a no-op
• All existing tests continue to pass

[Copilot]

Pull request overview

Adds support for automatically loading a per-user local override config file (e.g. .shopware-project.local.yml) and merging it on top of the main project config, with YAML tags to control merge semantics (!reset, !override).

Changes:

• Adds YAML node scanning + map-merge utilities to implement !reset and !override semantics for local overrides.
• Updates ReadConfig to detect and apply <config>.local.(yml|yaml) overrides.
• Adds unit tests covering filename derivation and merge behaviors (scalar overrides, slice append/reset, map override, include interaction, and empty local file).

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 2 comments.

File	Description
internal/shop/config_override.go	Implements local override filename derivation and YAML merge logic with !reset/!override.
internal/shop/config.go	Integrates local override detection + merged-config loading into ReadConfig.
internal/shop/config_override_test.go	Adds tests for local override filename derivation and merge semantics.

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.

You can also share your feedback on Copilot code review. Take the survey.