Fix all audit issues: survival check performance, display consistency, atomic config write, credential validation, TP null handling, highest_open preservation, stale docstring

config.py

@@ -13,14 +13,11 @@ As equity grows, the grid tightens (more orders = more frequent fills = more pro
 
 SURVIVAL RULE:
 --------------
-The bot calculates whether the account can survive a X% drop from the highest
-open position without being margin called. If not safe, no new orders are placed.
-Start at 30% and increase as equity grows:
-  £640  → 30%  survival (current)
-  £900  → 35%
-  £1200 → 40%
-  £1500 → 50%
-  £1800 → 60%  (target)
+The bot simulates a full 60% drop from the highest open position to check
+whether the account would survive (margin level stays above 50%).
+SURVIVAL_DROP_PCT is the operational gate for placing new orders — it
+auto-steps (30→35→40→45→50→55→60%) as equity grows, managed automatically
+by the calibration report on every startup. Do not edit it manually.
 
 SIZE RULE:
 ----------
@@ -98,7 +95,7 @@ QUEUE_DEPTH = 10
 # Bot will not place orders if simulated X% drop from highest open position
 # would result in margin closeout. Increase this as equity grows.
 # Current safe value for £640 equity = 30%. Target = 60%.
-SURVIVAL_DROP_PCT = 40.0
+SURVIVAL_DROP_PCT = 35.0
 
 # Capital.com retail margin rate for shares CFDs (5:1 leverage = 20% margin)
 MARGIN_RATE = 0.20