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.

.claude/settings.json

@@ -0,0 +1,15 @@
+{
+  "hooks": {
+    "PostToolUse": [
+      {
+        "matcher": "Write|Edit",
+        "hooks": [
+          {
+            "type": "command",
+            "command": "f=$(python3 -c 'import json,sys;print(json.load(sys.stdin).get(\"tool_input\",{}).get(\"file_path\",\"\"))'); case \"$f\" in */ui/*) cd ui && bun fix --skip=correctness/noUnusedImports ;; *.py) uv run ruff format \"$f\" && uv run ruff check --fix \"$f\" ;; esac"
+          }
+        ]
+      }
+    ]
+  }
+}