fix: resolve linting issues in token efficiency implementation

- Fix ambiguous variable names (l → layer)
- Remove unused imports and variables
- Organize import statements

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

src/brain/cache.py

@@ -13,8 +13,8 @@ import hashlib
 import json
 import logging
 import time
-from dataclasses import dataclass, field
-from typing import Any, TYPE_CHECKING
+from dataclasses import dataclass
+from typing import TYPE_CHECKING, Any
 
 if TYPE_CHECKING:
     from src.brain.gemini_client import TradeDecision
@@ -26,7 +26,7 @@ logger = logging.getLogger(__name__)
 class CacheEntry:
     """Cached decision with metadata."""
 
-    decision: "TradeDecision"
+    decision: TradeDecision
     cached_at: float  # Unix timestamp
     hit_count: int = 0
     market_data_hash: str = ""

src/brain/context_selector.py

@@ -191,7 +191,7 @@ class ContextSelector:
         selected_layers = [layer for layer, score in scores.items() if score >= min_score]
 
         # Sort by score (descending)
-        selected_layers.sort(key=lambda l: scores[l], reverse=True)
+        selected_layers.sort(key=lambda layer: scores[layer], reverse=True)
 
         total_score = sum(scores[layer] for layer in selected_layers)
 

src/brain/gemini_client.py

@@ -19,9 +19,9 @@ from typing import Any
 
 from google import genai
 
-from src.config import Settings
 from src.brain.cache import DecisionCache
 from src.brain.prompt_optimizer import PromptOptimizer
+from src.config import Settings
 
 logger = logging.getLogger(__name__)
 

src/brain/prompt_optimizer.py

@@ -14,7 +14,6 @@ import re
 from dataclasses import dataclass
 from typing import Any
 
-
 # Abbreviation mapping for common terms
 ABBREVIATIONS = {
     "price": "P",