feat(ui): add configurable input panel max rows and horizontal scrolling

- Introduce `ui.input_max_rows` (default 5) to control how many rows the input panel expands before scrolling.
- Bump `CONFIG_SCHEMA_VERSION` to **1.2.0** and update migration documentation.
- Update `configuration.md` and migration guide to describe the new setting.
- Adjust TUI height calculation to respect `input_max_rows` and add horizontal scrolling support for long lines.
- Add `unicode-segmentation` dependency for proper grapheme handling.

crates/owlen-core/src/config.rs

@@ -11,7 +11,7 @@ use std::time::Duration;
 pub const DEFAULT_CONFIG_PATH: &str = "~/.config/owlen/config.toml";
 
 /// Current schema version written to `config.toml`.
-pub const CONFIG_SCHEMA_VERSION: &str = "1.1.0";
+pub const CONFIG_SCHEMA_VERSION: &str = "1.2.0";
 
 /// Core configuration shared by all OWLEN clients
 #[derive(Debug, Clone, Serialize, Deserialize)]
@@ -706,6 +706,8 @@ pub struct UiSettings {
     pub wrap_column: u16,
     #[serde(default = "UiSettings::default_show_onboarding")]
     pub show_onboarding: bool,
+    #[serde(default = "UiSettings::default_input_max_rows")]
+    pub input_max_rows: u16,
 }
 
 impl UiSettings {
@@ -732,6 +734,10 @@ impl UiSettings {
     const fn default_show_onboarding() -> bool {
         true
     }
+
+    const fn default_input_max_rows() -> u16 {
+        5
+    }
 }
 
 impl Default for UiSettings {
@@ -743,6 +749,7 @@ impl Default for UiSettings {
             show_role_labels: Self::default_show_role_labels(),
             wrap_column: Self::default_wrap_column(),
             show_onboarding: Self::default_show_onboarding(),
+            input_max_rows: Self::default_input_max_rows(),
         }
     }
 }