feat: disable automatic full-workspace indexing for multi-root workspaces

[roomote]

This PR attempts to address Issue #10569. Feedback and guidance are welcome.

Problem

Multi-root workspaces cause local LLM DoS/Timeouts when Roo Code indexes all workspace folders simultaneously, overwhelming local embedding providers like Ollama.

Solution

This PR adds two new settings to control codebase indexing behavior:

1. Auto-start indexing (codebaseIndexAutoStart): Controls whether indexing starts automatically when opening a workspace. Default: true (existing behavior). Users can disable this for multi-root workspaces or when using resource-constrained local embedding providers.

2. Maximum concurrent indexing (codebaseIndexMaxConcurrent): Limits how many workspace folders can be indexed simultaneously. Default: 1 (sequential). Range: 1-10. Lower values reduce resource usage but take longer to complete.

Changes

• Added codebaseIndexAutoStart and codebaseIndexMaxConcurrent settings to types
• Updated config-manager.ts to load and expose new settings via getters
• Implemented queue-based initialization in extension.ts that respects concurrency limits
• Added UI controls in CodeIndexPopover.tsx (checkbox for auto-start, slider for max concurrent)
• Added translation strings for new UI labels
• Added unit tests for new config-manager getters

Testing

• Unit tests pass (82 tests)
• Manual testing with multi-root workspace and Ollama

Edge Cases Covered

• Single workspace folder (works as before with default settings)
• Multi-root workspace with auto-start disabled (no indexing until manually triggered)
• Multi-root workspace with concurrent limit of 1 (sequential indexing)
• Multi-root workspace with higher concurrent limit (parallel indexing)

Fixes #10569

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Important

Adds settings to control codebase indexing auto-start and concurrency, updates configuration management, and enhances UI with new controls and translations.

• Behavior:
  • Adds codebaseIndexAutoStart and codebaseIndexMaxConcurrent settings to control indexing behavior in codebase-index.ts.
  • Implements queue-based initialization in extension.ts to respect concurrency limits.
  • UI updates in CodeIndexPopover.tsx to include controls for new settings.
• Configuration:
  • Updates CodeIndexConfigManager in config-manager.ts to load and expose new settings.
  • Adds unit tests in config-manager.spec.ts for new settings.
• UI:
  • Adds checkbox for auto-start and slider for max concurrent indexing in CodeIndexPopover.tsx.
  • Adds translation strings for new UI labels in settings.json.

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[roomote]

Rooviewer   See task on Roo Cloud

Reviewed this PR and found no issues. The implementation is solid:

• New settings (codebaseIndexAutoStart, codebaseIndexMaxConcurrent) are properly defined with schema validation
• Queue-based initialization in extension.ts correctly manages concurrent indexing
• Config manager properly loads settings with appropriate defaults
• UI controls in CodeIndexPopover work as expected
• Tests comprehensively cover the new functionality

_{Mention @roomote in a comment to request specific changes to this pull request or fix all unresolved issues.}