**docs: remove outdated statistics-related documentation and add standards**

- **Removed Files**:
  - Deleted outdated statistics documentation files (`statistics.md`, `statistics-flush-solution.md`, `statistics-summary.md`) to clean up the repository and avoid confusion.

- **Added Standards**:
  - Introduced `DOCUMENTATION_STANDARDS.md` to outline naming conventions and troubleshooting practices for more consistent and maintainable project documentation.

- **Tests**:
  - Added a new test file `edge-cases.test.ts` to verify handling of edge cases, ensuring robust behavior against boundary values and invalid inputs.

**Purpose**: Cleans up deprecated documentation while introducing concrete standards for maintaining and updating documentation. Enhances test coverage for unusual or boundary inputs, improving overall system resilience.

src/utils/distance.ts

@@ -155,7 +155,7 @@ export async function calculateDistancesBatch(
                 global.TextEncoder = util.TextEncoder
               }
               if (typeof global.TextDecoder === 'undefined') {
-                global.TextDecoder = util.TextDecoder
+                global.TextDecoder = util.TextDecoder as unknown as typeof TextDecoder
               }
             }