Bugfix/vtrx timewindow adjustment (#48)

* lengthen MAX_HISTORY_SECONDS to 1 week

* time window note

subsystem/vtrx/README.md

@@ -16,6 +16,10 @@ Parser expects semicolon-separated string containing at least three fields:
 3. switch states in binary format
 4. Optional additional error messages
 
+### Data Retention and Time Window
+The subsystem maintains a rolling buffer of pressure readings with the following characteristics:
+- Max history: 168 hours (1 week)
+- Data points are automatically trimmed beyond this window
 
 ### GUI Elements
 - Real-time pressure plotting with configurable time window

subsystem/vtrx/vtrx.py

@@ -52,7 +52,7 @@ def __init__(self, parent, serial_port='COM7', baud_rate=9600, logger=None):
         self.logger = logger
         self.data_queue = queue.Queue()
 
-        self.MAX_HISTORY_SECONDS = 36000 # 10 hours
+        self.MAX_HISTORY_SECONDS = 7 * 24 * 60 * 60 # 7 days in seconds
         self.full_history_x = []    # Complete timestamp history
         self.full_history_y = []    # Complete pressure history
         self.x_data = []            # Display window data
@@ -349,7 +349,14 @@ def setup_gui(self):
             ("30 min", 1800),
             ("1 hour", 3600),
             ("5 hour", 18000),
-            ("10 hour", 36000)
+            ("10 hour", 36000),
+            ("1 day", 86400),
+            ("2 days", 172800),
+            ("3 days", 259200),
+            ("4 days", 345600),
+            ("5 days", 432000),
+            ("6 days", 518400),
+            ("Max", self.MAX_HISTORY_SECONDS)
         ]
 
         self.time_window_var = tk.StringVar(value="5 min")