feat(ui,infra): SvelteKit ui scaffold, Makefile, pre-commit, claude hooks

ui/: SvelteKit 2 + Svelte 5 + Tailwind 4 + shadcn-svelte (luma, lucide)
on bun with ultracite; adapter-static with SPA fallback; theme tokens
taken from msos. Dockerfile gains a bun stage that builds ui/build.
Makefile and pre-commit cover ruff, ty, ultracite and svelte-check;
.claude settings run the matching fixer after edits. docs/PRODUCT.md
captures product truth for the UI work.

Dockerfile

@@ -30,6 +30,14 @@ COPY . /app
 RUN --mount=type=cache,target=/root/.cache/uv \
     uv sync --frozen --no-dev --extra prod
 
+# ---- UI: SvelteKit SPA built with bun ----
+FROM oven/bun:1-slim AS ui
+WORKDIR /ui
+COPY ui/package.json ui/bun.lock ./
+RUN bun install --frozen-lockfile
+COPY ui ./
+RUN bun --bun svelte-kit sync && bun --bun run build
+
 # ---- Runtime ----
 FROM python:3.13-slim AS runtime
 RUN apt-get update \
@@ -59,6 +67,7 @@ RUN bun install -g --trust @anthropic-ai/claude-code \
 
 COPY --from=builder /app/.venv /app/.venv
 COPY --from=builder /app /app
+COPY --from=ui /ui/build /app/ui/build
 WORKDIR /app
 
 ENTRYPOINT ["python", "-m"]