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/main.rs

@@ -9,6 +9,7 @@ mod docs;
 mod files;
 mod git;
 mod images;
+mod lsp;
 mod mcp;
 mod permission;
 mod prompts;
@@ -42,6 +43,7 @@ async fn main() -> Result<()> {
     let _ = sandbox::probe().await;
     let bind = cfg.server.bind.clone();
     let app = app::App::new(path, cfg).await?;
+    lsp::spawn_reaper(app.clone());
     let router = api::router(app);
     let listener = tokio::net::TcpListener::bind(&bind).await?;
     tracing::info!("listening on http://{bind}");