Restore per-path conflict resolution strategies in module discovery

[synthable]

Problem

The refactoring to use ModuleRegistry has caused a regression in conflict resolution functionality. Previously, users could configure different conflict strategies for different module paths in modules.config.yml:

localModulePaths:
  - path: './strict-modules'
    onConflict: 'error'
  - path: './flexible-modules' 
    onConflict: 'warn'

However, the current ModuleRegistry implementation only supports a single global conflict strategy set at construction time.

Impact

• Users can no longer have different conflict resolution behaviors for different module paths
• This is a functional regression from the previous implementation
• The configuration schema still allows per-path strategies but they're ignored

Potential Solutions

1. Extend ModuleRegistry: Add support for per-source conflict strategies to the ModuleSource interface and ModuleRegistry implementation
2. Multiple Registries: Use separate registries per conflict strategy and merge results
3. CLI-level Resolution: Handle per-path conflict logic in the CLI layer while using 'warn' strategy in the registry

Current Workaround

The current implementation uses a global strategy for the entire registry, which means all paths inherit the same conflict resolution behavior.

Related Files

• packages/copilot-instructions-cli/src/utils/module-discovery.ts
• packages/ums-lib/src/core/registry/module-registry.ts
• packages/ums-lib/src/types/index.ts (ModuleSource interface)

Priority: Medium - This affects advanced users who rely on per-path conflict strategies.