feat: add --generate-config mode to output default config

Co-authored-by: aider (openai/andrew/openrouter/deepseek/deepseek-chat-v3.1) <aider@aider.chat>

src/modes/generate_config.rs

@@ -0,0 +1,57 @@
+use anyhow::Result;
+use clap::Command;
+use serde::{Deserialize, Serialize};
+use serde_yaml;
+
+#[derive(Debug, Serialize, Deserialize)]
+struct DefaultConfig {
+    dir: Option<String>,
+    list_format: Vec<String>,
+    human_readable: bool,
+    output_format: Option<String>,
+    quiet: bool,
+    server: Option<ServerConfig>,
+    compression_plugins: Vec<String>,
+    meta_plugins: Vec<String>,
+}
+
+#[derive(Debug, Serialize, Deserialize)]
+struct ServerConfig {
+    address: Option<String>,
+    port: Option<u16>,
+    password_file: Option<String>,
+    password: Option<String>,
+    password_hash: Option<String>,
+}
+
+pub fn mode_generate_config(_cmd: &mut Command, _settings: &crate::config::Settings) -> Result<()> {
+    // Create a default configuration
+    let default_config = DefaultConfig {
+        dir: Some("~/.local/share/keep".to_string()),
+        list_format: vec![
+            "id".to_string(),
+            "time".to_string(),
+            "size".to_string(),
+            "tags".to_string(),
+            "meta:hostname".to_string(),
+        ],
+        human_readable: false,
+        output_format: Some("table".to_string()),
+        quiet: false,
+        server: Some(ServerConfig {
+            address: Some("127.0.0.1".to_string()),
+            port: Some(8080),
+            password_file: None,
+            password: None,
+            password_hash: None,
+        }),
+        compression_plugins: vec![],
+        meta_plugins: vec![],
+    };
+    
+    // Serialize to YAML and print to stdout
+    let yaml = serde_yaml::to_string(&default_config)?;
+    println!("{}", yaml);
+    
+    Ok(())
+}