feat(ui): simplify AppMode minibuffer handling and panel rendering

Refactor AppMode to use MinibufferConfig for all text-entry modes. Update
command implementations to use new mode constructors. Introduce
PanelContent trait and replace panel structs with content types. Adjust
rendering to use Panel::new and minibuffer configuration. Update imports
and add MinibufferConfig struct. No functional changes; all behavior
preserved.

Co-Authored-By: fiddlerwoaroof/git-smart-commit (bartowski/nvidia_Nemotron-Cascade-2-30B-A3B-GGUF)

src/ui/app.rs

@@ -7,6 +7,8 @@ use std::time::{Duration, Instant};
 
 use std::rc::Rc;
 
+use ratatui::style::Color;
+
 use crate::command::cmd::CmdContext;
 use crate::command::keymap::{Keymap, KeymapSet};
 use crate::import::wizard::ImportWizard;
@@ -29,40 +31,126 @@ pub struct DrillState {
     pub pending_edits: std::collections::HashMap<(usize, String), String>,
 }
 
+/// Display configuration for the bottom-bar minibuffer.
+/// Carried structurally by text-entry `AppMode` variants.
+#[derive(Debug, Clone, PartialEq)]
+pub struct MinibufferConfig {
+    pub buffer_key: &'static str,
+    pub prompt: String,
+    pub color: Color,
+}
+
 #[derive(Debug, Clone, PartialEq)]
 pub enum AppMode {
     Normal,
     Editing {
-        buffer: String,
+        minibuf: MinibufferConfig,
     },
     FormulaEdit {
-        buffer: String,
+        minibuf: MinibufferConfig,
     },
     FormulaPanel,
     CategoryPanel,
     /// Quick-add a new category: Enter adds and stays open, Esc closes.
     CategoryAdd {
-        buffer: String,
+        minibuf: MinibufferConfig,
     },
     /// Quick-add items to `category`: Enter adds and stays open, Esc closes.
     ItemAdd {
         category: String,
-        buffer: String,
+        minibuf: MinibufferConfig,
     },
     ViewPanel,
     TileSelect,
     ImportWizard,
     ExportPrompt {
-        buffer: String,
+        minibuf: MinibufferConfig,
     },
     /// Vim-style `:` command line
     CommandMode {
-        buffer: String,
+        minibuf: MinibufferConfig,
     },
     Help,
     Quit,
 }
 
+impl AppMode {
+    /// Extract the minibuffer config from text-entry modes, if present.
+    pub fn minibuffer(&self) -> Option<&MinibufferConfig> {
+        match self {
+            Self::Editing { minibuf, .. }
+            | Self::FormulaEdit { minibuf, .. }
+            | Self::CommandMode { minibuf, .. }
+            | Self::CategoryAdd { minibuf, .. }
+            | Self::ItemAdd { minibuf, .. }
+            | Self::ExportPrompt { minibuf, .. } => Some(minibuf),
+            _ => None,
+        }
+    }
+
+    pub fn editing() -> Self {
+        Self::Editing {
+            minibuf: MinibufferConfig {
+                buffer_key: "edit",
+                prompt: "edit: ".into(),
+                color: Color::Green,
+            },
+        }
+    }
+
+    pub fn formula_edit() -> Self {
+        Self::FormulaEdit {
+            minibuf: MinibufferConfig {
+                buffer_key: "formula",
+                prompt: "formula: ".into(),
+                color: Color::Cyan,
+            },
+        }
+    }
+
+    pub fn command_mode() -> Self {
+        Self::CommandMode {
+            minibuf: MinibufferConfig {
+                buffer_key: "command",
+                prompt: ":".into(),
+                color: Color::Yellow,
+            },
+        }
+    }
+
+    pub fn category_add() -> Self {
+        Self::CategoryAdd {
+            minibuf: MinibufferConfig {
+                buffer_key: "category",
+                prompt: "new category: ".into(),
+                color: Color::Yellow,
+            },
+        }
+    }
+
+    pub fn item_add(category: String) -> Self {
+        let prompt = format!("add item to {category}: ");
+        Self::ItemAdd {
+            category,
+            minibuf: MinibufferConfig {
+                buffer_key: "item",
+                prompt,
+                color: Color::Green,
+            },
+        }
+    }
+
+    pub fn export_prompt() -> Self {
+        Self::ExportPrompt {
+            minibuf: MinibufferConfig {
+                buffer_key: "export",
+                prompt: "export path: ".into(),
+                color: Color::Yellow,
+            },
+        }
+    }
+}
+
 pub struct App {
     pub model: Model,
     pub file_path: Option<PathBuf>,