Fix import extension mismatch in tool gating tests

**Problem:**
Test files are importing from .ts extensions while implementation uses .js extensions, which breaks ES module compatibility.

**Location:**
- `tests/unit/gating/toolset-registry.test.ts` imports from `.ts` files
- `src/gating/toolset-registry.ts` imports from `.js` files

**Impact:**
This inconsistency can cause module resolution failures in ES module environments.

**Solution:**
Standardize import extensions across test and implementation files.

**Related PR:** https://github.com/KHAEntertainment/claude-flow/pull/2
**Requested by:** @KHAEntertainment