fix(context-overflow): parse Unicode box-drawing separators and K/M suffixes

The context bar regex used ASCII pipe '|' but the actual tmux status bar
uses U+2502 '│' (box drawings light vertical). The primary pattern
never matched, falling back to percentage-only extraction with
model="unknown" and used=total=0.

Fixed:
- Updated pattern to match '│' separator
- Support K/M suffixes (8.19K, 65.5K, 262.1K etc.)
- Support decimals in token counts
- parse_count() converts K/M to numeric values

Now all 4 acceptance criteria are met:
- Context % + model + used/total extracted from every pane
- 60% triggers summarization prompt (logic already present)
- 80% triggers urgent commit-and-restart (logic already present)
- Context levels fully logged to tmux-state.json manifest

Closes #510

bin/context-overflow-guard.py

@@ -106,7 +106,7 @@ def capture_pane(session, window_name, pane_index):
     
     # Look for context bar pattern: ⚕ model | used/total | % | time
     # Example: ⚕ mimo-v2-pro | 45,230/131,072 | 34% | 12m remaining
-    context_pattern = r"⚕\s+([^|]+)\|\s*([\d,]+)/([\d,]+)\|\s*(\d+)%\|"
+    context_pattern = r"⚕\s+([^│]+)\s*│\s*([\d.]+[KM]?)/([\d.]+[KM]?)\s*│.*?([\d]+)%\s*│"
     
     lines = output.split("\n")
     for line in lines:
@@ -117,12 +117,24 @@ def capture_pane(session, window_name, pane_index):
             total_str = match.group(3).replace(",", "")
             percent = int(match.group(4))
             
+            # Parse counts that may have K/M suffix
+            def parse_count(s):
+                s = s.strip().upper()
+                if not s:
+                    return 0
+                multiplier = 1
+                if 'K' in s:
+                    multiplier = 1000
+                    s = s.replace('K', '')
+                elif 'M' in s:
+                    multiplier = 1000000
+                    s = s.replace('M', '')
                 try:
-                used = int(used_str)
+                    return int(float(s) * multiplier)
-                total = int(total_str)
                 except:
-                used = 0
+                    return 0
-                total = 0
+            used = parse_count(used_str)
+            total = parse_count(total_str)
             
             return {
                 "model": model,