refactor: remove Redis benchmark system

Remove the Redis-backed performance benchmarking in favor of the new
lightweight file-based tracing system which provides better debugging
capabilities for local development.

- Delete src/core/benchmarks.py
- Remove ENABLE_BENCHMARKS, REDIS_BENCHMARK_DB, redis_url from config
- Update memory_cache comment (now uses DB 1)

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

src/core/config.py

@@ -101,10 +101,6 @@ class Config(BaseSettings):
         default=6379,
         description="Redis server port"
     )
-    REDIS_BENCHMARK_DB: int = Field(
-        default=6,
-        description="Redis database number for benchmarks"
-    )
     REDIS_TIMEOUT: int = Field(
         default=5,
         description="Redis connection timeout in seconds"
@@ -158,7 +154,7 @@ class Config(BaseSettings):
         description="Ollama model for embeddings"
     )
 
-    # Redis Memory Database (separate from benchmarks)
+    # Redis Memory Database
     REDIS_MEMORY_DB: int = Field(
         default=1,
         description="Redis database number for memory cache"
@@ -173,7 +169,6 @@ class Config(BaseSettings):
         default=None,
         description="Logging level (auto-set based on environment if not specified)"
     )
-    ENABLE_BENCHMARKS: bool = Field(default=True, description="Enable performance benchmarking")
 
     # User Configuration
     DEFAULT_USER: str | None = Field(
@@ -190,11 +185,6 @@ class Config(BaseSettings):
     CORS_ALLOW_METHODS: list[str] = ["*"]
     CORS_ALLOW_HEADERS: list[str] = ["*"]
 
-    @property
-    def redis_url(self) -> str:
-        """Construct Redis connection URL for benchmarks."""
-        return f"redis://{self.REDIS_HOST}:{self.REDIS_PORT}/{self.REDIS_BENCHMARK_DB}"
-
     @property
     def redis_memory_url(self) -> str:
         """Construct Redis connection URL for memory cache."""