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>

Dockerfile

@@ -29,6 +29,9 @@ RUN apt-get update && apt-get install -y --no-install-recommends \
         build-essential pkg-config libssl-dev cmake zlib1g-dev binutils-multiarch \
         chromium fonts-dejavu-core fonts-noto-color-emoji poppler-utils openmpt123 \
     && rm -rf /var/lib/apt/lists/*
+# Language servers for diagnostics after edits (rust-analyzer/gopls/clangd can be
+# installed by agents: rustup component add rust-analyzer, go install …).
+RUN npm install -g typescript@5 typescript-language-server pyright && npm cache clean --force
 COPY --from=server /src/server/target/release/codecraft /usr/local/bin/codecraft
 COPY --from=web /web/dist /app/web
 COPY server/ghidra /app/ghidra