feat: add user-selectable aspect ratio and resolution per thread

Adds a two-step new thread modal: step one picks mode, step two
configures aspect ratio (Art mode only, six options) and resolution
(all modes: 1K/2K/4K). Settings are stored on the thread and forwarded
to the Gemini API on every send, retry, and edit. Also regenerates
icon.ico with Python to produce a clean all-BMP ICO compatible with
both Tauri's proc macro and llvm-rc cross-compilation.

src-tauri/src/gemini.rs

@@ -115,31 +115,18 @@ fn build_user_gemini_parts(
     }
 }
 
-pub struct GeminiCallParams {
-    pub mode: String,
-    pub aspect_ratio: Option<String>,
-    pub image_size: String,
-    pub user_text: Option<String>,
-    pub user_image_base64: Option<String>,
-    pub user_image_mime: Option<String>,
-}
-
 pub async fn call_gemini(
     api_key: String,
+    mode: String,
+    aspect_ratio: Option<String>,
+    image_size: String,
     history: Vec<ThreadMessage>,
-    params: GeminiCallParams,
+    user_text: Option<String>,
+    user_image_base64: Option<String>,
+    user_image_mime: Option<String>,
 ) -> Result<(Vec<MessagePart>, f64), String> {
     let client = reqwest::Client::new();
 
-    let GeminiCallParams {
-        mode,
-        aspect_ratio,
-        image_size,
-        user_text,
-        user_image_base64,
-        user_image_mime,
-    } = params;
-
     let is_first_message = history.is_empty();
 
     let mut contents: Vec<Value> = history

src-tauri/src/lib.rs

@@ -1,7 +1,7 @@
 mod gemini;
 mod storage;
 
-use gemini::{call_gemini, read_reference_image_base64, GeminiCallParams};
+use gemini::{call_gemini, read_reference_image_base64};
 use serde::Serialize;
 use storage::{
     delete_thread_from_disk, load_config_from_disk, load_threads_from_disk, save_config_to_disk,
@@ -46,7 +46,6 @@ async fn save_config(config: Config) -> Result<(), String> {
 }
 
 #[tauri::command]
-#[allow(clippy::too_many_arguments)]
 async fn send_message(
     api_key: String,
     mode: String,
@@ -59,15 +58,13 @@ async fn send_message(
 ) -> Result<SendMessageResult, String> {
     let (parts, cost_usd) = call_gemini(
         api_key,
-        history,
-        GeminiCallParams {
         mode,
         aspect_ratio,
         image_size,
+        history,
         user_text,
         user_image_base64,
         user_image_mime,
-        },
     )
     .await?;
     Ok(SendMessageResult { parts, cost_usd })