fix(P03): confidence_signal emits literal 0.90/0.40 (T-3.6)

---ci---
phase: 3
milestone: v1.0
status: execute
persona: backend-engineer
task: T-3.6
requirements:
  covered: [REQ-08]
---/ci---

Wave 2, task T-3.6. json.dumps collapsed 0.90 -> 0.9; emit literal two-decimal score per contract while remaining valid JSON.

scripts/confidence_signal.py

@@ -37,15 +37,17 @@ def main() -> int:
     )
 
     if proc.returncode == 0:
-        score = 0.90
+        score = "0.90"
         # POLICY_PASS is the expected stdout; strip any trailing whitespace.
         reason = proc.stdout.strip() or "POLICY_PASS"
     else:
-        score = 0.40
+        score = "0.40"
         # The violation code (e.g. "POLICY_VIOLATION:PUBLIC_INGRESS") is on stdout.
         reason = proc.stdout.strip() or "POLICY_VIOLATION:UNKNOWN"
 
-    print(json.dumps({"score": score, "reason": reason}))
+    # Emit with literal score (two-decimal form per the contract) and a quoted
+    # reason. Constructed manually so json.dumps does not collapse 0.90 -> 0.9.
+    print('{"score": ' + score + ', "reason": ' + json.dumps(reason) + '}')
     return 0