[FEATURE] Add Workspace Symbol Search

[FrilLab]

Problem

The extension cannot currently discover where a symbol is defined or referenced across the workspace.

This limits contextual understanding for translations and explanations.

Proposed Solution

Use VSCode symbol APIs to locate:

• Functions
• Classes
• Interfaces
• Variables
• Types

Relevant symbol information can be included in translation requests.

Alternatives

• Simple text search
• Project indexing only

Additional Context

This feature acts as a bridge between project indexing and retrieval-based context systems.