Add analysis preview to case list

Introduce a `preview_lines` setting in `users.toml` to control the
number of visible lines for the analysis preview in the case list. This
feature extracts the first paragraph of the `document.md` file, strips
markdown formatting, and displays it, capped by the configured
`preview_lines`. The actual line clamping is handled client-side via CSS
`line-clamp`.

server/src/config.rs

@@ -33,6 +33,14 @@ fn default_window_hours() -> u32 {
     72
 }
 
+/// Default number of analysis-preview lines rendered under each case on
+/// the list view when the user entry omits `preview_lines`. Two lines
+/// show the first sentence of the LLM output in most cases without
+/// dominating the list row.
+fn default_preview_lines() -> u32 {
+    2
+}
+
 /// A single user entry from users.toml.
 #[derive(Debug, Deserialize)]
 pub struct User {
@@ -51,6 +59,14 @@ pub struct User {
     /// apply no additional time filter.
     #[serde(default = "default_window_hours")]
     pub window_hours: u32,
+    /// Number of analysis-preview lines rendered under each case row on
+    /// the list view. The preview itself is always the first paragraph of
+    /// `document.md`; this value only controls how many *visual* lines
+    /// the browser will show before truncating with `…`. Applied via a
+    /// CSS `line-clamp` custom property, so a single server value adapts
+    /// to any viewport width.
+    #[serde(default = "default_preview_lines")]
+    pub preview_lines: u32,
 }
 
 /// Wrapper for deserializing the [[user]] array from TOML.
@@ -290,6 +306,7 @@ mod tests {
             whisper: WhisperUserSettings::default(),
             retention: RetentionUserSettings::default(),
             window_hours: default_window_hours(),
+            preview_lines: default_preview_lines(),
         }
     }
 
@@ -344,6 +361,33 @@ mod tests {
         assert_eq!(r.auto_delete_days, 30);
     }
 
+    #[test]
+    fn parses_user_without_preview_lines_defaults_to_2() {
+        let toml_str = r#"
+            [[user]]
+            slug = "a"
+            api_key = "k1"
+            web_password = ""
+            role = "doctor"
+        "#;
+        let parsed: UsersFile = toml::from_str(toml_str).unwrap();
+        assert_eq!(parsed.user[0].preview_lines, 2);
+    }
+
+    #[test]
+    fn parses_user_with_explicit_preview_lines() {
+        let toml_str = r#"
+            [[user]]
+            slug = "a"
+            api_key = "k1"
+            web_password = ""
+            role = "doctor"
+            preview_lines = 5
+        "#;
+        let parsed: UsersFile = toml::from_str(toml_str).unwrap();
+        assert_eq!(parsed.user[0].preview_lines, 5);
+    }
+
     #[test]
     fn parses_user_with_partial_retention_block() {
         let toml_str = r#"