fix(security): expand Password PII patterns; add regression tests

Two credential patterns were missing from the PiiDetector, confirmed
by live audit log showing was_pii_redacted: false with plaintext creds:

1. Abbreviated key form (pass: abc123!!): the pattern only matched
   password|passwd|pwd. Added pass, passphrase, secret with a word
   boundary to prevent substring false positives (bypass:, compass:).

2. Natural language form (Is the password password123 good): added a
   second Password sub-pattern for keyword-adjacent values without a
   key separator. Value must contain a digit or special char to avoid
   flagging plain words (password strength, password policy).

5 new regression tests added. 233/233 Rust tests pass.

src-tauri/src/pii/detector.rs

@@ -86,6 +86,91 @@ mod tests {
         assert!(spans.iter().any(|s| s.pii_type == "Bearer"));
     }
 
+    #[test]
+    fn test_detect_password_keyword() {
+        let detector = PiiDetector::new();
+        // Full keyword forms
+        assert!(detector
+            .detect("password: hunter2")
+            .iter()
+            .any(|s| s.pii_type == "Password"));
+        assert!(detector
+            .detect("passwd=hunter2")
+            .iter()
+            .any(|s| s.pii_type == "Password"));
+        assert!(detector
+            .detect("pwd: hunter2")
+            .iter()
+            .any(|s| s.pii_type == "Password"));
+    }
+
+    #[test]
+    fn test_detect_pass_abbreviation() {
+        let detector = PiiDetector::new();
+        // Abbreviated form used in credential files (was the failing case)
+        let text = "user: alpha\npass: abc123!!";
+        let spans = detector.detect(text);
+        assert!(
+            spans.iter().any(|s| s.pii_type == "Password"),
+            "Expected Password span for 'pass: abc123!!' — got: {spans:?}"
+        );
+    }
+
+    #[test]
+    fn test_detect_secret_keyword() {
+        let detector = PiiDetector::new();
+        assert!(detector
+            .detect("secret: mysecretvalue")
+            .iter()
+            .any(|s| s.pii_type == "Password"));
+        assert!(detector
+            .detect("passphrase: correct horse battery staple")
+            .iter()
+            .any(|s| s.pii_type == "Password"));
+    }
+
+    #[test]
+    fn test_detect_password_natural_language() {
+        let detector = PiiDetector::new();
+        // Direct juxtaposition: "password <value>" (was the second failing case)
+        let spans = detector.detect("Is the password password123 good");
+        assert!(
+            spans.iter().any(|s| s.pii_type == "Password"),
+            "Expected Password span for natural-language 'password password123' — got: {spans:?}"
+        );
+        // "password is X"
+        assert!(detector
+            .detect("my password is hunter2")
+            .iter()
+            .any(|s| s.pii_type == "Password"));
+        // Value must have digit or special — plain words should not trigger
+        assert!(
+            !detector
+                .detect("password strength")
+                .iter()
+                .any(|s| s.pii_type == "Password"),
+            "False positive: 'password strength' should not match"
+        );
+        assert!(
+            !detector
+                .detect("password policy")
+                .iter()
+                .any(|s| s.pii_type == "Password"),
+            "False positive: 'password policy' should not match"
+        );
+    }
+
+    #[test]
+    fn test_password_no_false_positive_bypass() {
+        let detector = PiiDetector::new();
+        // "bypass" contains "pass" as a substring — must NOT match
+        let spans = detector.detect("bypass: enabled");
+        assert!(
+            !spans.iter().any(|s| s.pii_type == "Password"),
+            "False positive: 'bypass:' should not match Password pattern"
+        );
+    }
+
     #[test]
     fn test_no_overlap() {
         let detector = PiiDetector::new();

src-tauri/src/pii/patterns.rs

@@ -22,10 +22,22 @@ pub fn get_patterns() -> Vec<(PiiType, Regex)> {
             )
             .unwrap(),
         ),
-        // Password
+        // Password (key=value / config file form) — word-boundary anchored
         (
             PiiType::Password,
-            Regex::new(r"(?i)(?:password|passwd|pwd)\s*[=:]\s*\S+").unwrap(),
+            Regex::new(
+                r"(?i)\b(?:password|passwd|passphrase|pass|pwd|secret)\s*[=:]\s*\S+",
+            )
+            .unwrap(),
+        ),
+        // Password (natural language form): "password is X", "password X"
+        // Value must contain at least one digit or special char to avoid flagging plain words.
+        (
+            PiiType::Password,
+            Regex::new(
+                r"(?i)\b(?:password|passwd|passphrase)\s+(?:is\s+|was\s+)?[A-Za-z0-9!@#$%^&*_\-+=@#,.]*[0-9!@#$%^&*_\-+=@#][A-Za-z0-9!@#$%^&*_\-+=@#,.]*",
+            )
+            .unwrap(),
         ),
         // SSN (check before phone to avoid partial matches)
         (