Add file badges, menu icons, LSP diagnostics, robust compaction

- Files in chat: preview with type/size badges and file name; attachment chips
- Menu and settings tabs with icons
- Heatmap: distinct colour for empty hours, hourly labels
- Context chip shows used/total tokens (e.g. 221k/240k) plus percent
- LSP client: diagnostics appended to edit/write results and a diagnostics tool
  (typescript-language-server, pyright, rust-analyzer, gopls, clangd; sandboxed)
- Compaction summarizes a plain transcript and retries once on empty output
- files/stat endpoint

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

server/src/config.rs

@@ -23,8 +23,43 @@ pub struct Config {
     pub images: ImagesConfig,
     pub sandbox: SandboxConfig,
     pub search: SearchConfig,
+    pub lsp: LspConfig,
 }
 
+/// Language servers for diagnostics after edits.
+#[derive(Debug, Clone, Deserialize, Serialize)]
+#[serde(default)]
+pub struct LspConfig {
+    pub enabled: bool,
+    /// Extra or overridden servers (built-in: rust, typescript, python, go, c).
+    pub servers: std::collections::BTreeMap<String, LspServer>,
+}
+
+impl Default for LspConfig {
+    fn default() -> Self {
+        Self { enabled: true, servers: Default::default() }
+    }
+}
+
+#[derive(Debug, Clone, Deserialize, Serialize)]
+pub struct LspServer {
+    pub command: String,
+    #[serde(default)]
+    pub args: Vec<String>,
+    /// File extensions without dot.
+    #[serde(default)]
+    pub extensions: Vec<String>,
+    /// Files that mark the project root (e.g. Cargo.toml).
+    #[serde(default)]
+    pub root_markers: Vec<String>,
+    /// initializationOptions sent to the server.
+    #[serde(default, skip_serializing_if = "serde_json::Value::is_null")]
+    pub init_options: serde_json::Value,
+    #[serde(default = "yes")]
+    pub enabled: bool,
+}
+
+
 /// Web search for the web_search tool.
 #[derive(Debug, Clone, Deserialize, Serialize)]
 #[serde(default)]