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>

web/src/styles.css

@@ -2090,3 +2090,117 @@ button.danger-solid {
   gap: 4px;
   min-width: 0;
 }
+
+/* --- files in chat (preview + type/size badges + name) ------------------------- */
+.file-figure {
+  display: inline-flex;
+  flex-direction: column;
+  gap: 4px;
+  margin: 6px 8px 6px 0;
+  max-width: min(100%, 640px);
+  vertical-align: top;
+}
+.file-preview {
+  min-width: 128px;
+  position: relative;
+  display: inline-block;
+  max-width: 100%;
+}
+.file-preview img {
+  margin: 0 !important;
+  display: block;
+}
+.file-badge {
+  font-size: 10px;
+  font-weight: 600;
+  letter-spacing: 0.03em;
+  line-height: 1;
+  padding: 3px 6px;
+  border-radius: 4px;
+  background: color-mix(in srgb, var(--bg0) 82%, transparent);
+  color: var(--fg1);
+  border: 1px solid var(--bg3);
+  white-space: nowrap;
+}
+.file-preview .file-badge {
+  position: absolute;
+  top: 6px;
+  pointer-events: none;
+  backdrop-filter: blur(4px);
+}
+.file-preview .file-badge.left {
+  left: 6px;
+}
+.file-preview .file-badge.right {
+  right: 6px;
+}
+.file-figure figcaption {
+  font-size: 12px;
+  color: var(--fg3);
+  overflow: hidden;
+  text-overflow: ellipsis;
+  white-space: nowrap;
+  max-width: 100%;
+}
+.file-figure figcaption a {
+  color: inherit;
+}
+.file-figure.thumb img {
+  height: 140px;
+  max-width: 260px;
+  object-fit: contain;
+}
+.msg-user .file-figure img {
+  max-height: 160px;
+  border-radius: 6px;
+}
+.user-files {
+  display: flex;
+  flex-wrap: wrap;
+  gap: 6px;
+  margin-top: 6px;
+}
+.file-chip {
+  display: inline-flex;
+  align-items: center;
+  gap: 6px;
+  max-width: 100%;
+  padding: 4px 8px;
+  border-radius: 6px;
+  border: 1px solid var(--bg3);
+  background: var(--bg1);
+  color: var(--fg1);
+  font-size: 12px;
+  text-decoration: none;
+  white-space: nowrap;
+  margin: 2px 0;
+}
+.file-chip:hover {
+  border-color: var(--accent);
+}
+.file-chip-name {
+  overflow: hidden;
+  text-overflow: ellipsis;
+  min-width: 0;
+}
+.file-chip-size {
+  color: var(--muted);
+}
+.file-chip .file-badge {
+  background: var(--bg2);
+  border: none;
+}
+.gallery .file-figure { margin: 0; max-width: none; display: flex; }
+
+.nav-icon {
+  display: inline-block;
+  width: 1.3em;
+  margin-right: 6px;
+  text-align: center;
+  font-size: 0.95em;
+}
+.sidebar-foot button {
+  display: flex;
+  align-items: center;
+  justify-content: flex-start;
+}