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.

ui/.vscode/extensions.json

@@ -0,0 +1,3 @@
+{
+  "recommendations": ["svelte.svelte-vscode", "bradlc.vscode-tailwindcss"]
+}

ui/.vscode/settings.json

@@ -0,0 +1,57 @@
+{
+  "files.associations": {
+    "*.css": "tailwindcss"
+  },
+  "editor.defaultFormatter": "esbenp.prettier-vscode",
+  "editor.formatOnPaste": true,
+  "editor.formatOnSave": true,
+  "emmet.showExpandedAbbreviation": "never",
+  "js/ts.tsdk.path": "node_modules/typescript/lib",
+  "js/ts.tsdk.promptToUseWorkspaceVersion": true,
+  "[css]": {
+    "editor.defaultFormatter": "biomejs.biome"
+  },
+  "[graphql]": {
+    "editor.defaultFormatter": "biomejs.biome"
+  },
+  "[html]": {
+    "editor.defaultFormatter": "biomejs.biome"
+  },
+  "[javascript]": {
+    "editor.defaultFormatter": "biomejs.biome"
+  },
+  "[javascriptreact]": {
+    "editor.defaultFormatter": "biomejs.biome"
+  },
+  "[json]": {
+    "editor.defaultFormatter": "biomejs.biome"
+  },
+  "[jsonc]": {
+    "editor.defaultFormatter": "biomejs.biome"
+  },
+  "[markdown]": {
+    "editor.defaultFormatter": "biomejs.biome"
+  },
+  "[mdx]": {
+    "editor.defaultFormatter": "biomejs.biome"
+  },
+  "[svelte]": {
+    "editor.defaultFormatter": "biomejs.biome"
+  },
+  "[typescript]": {
+    "editor.defaultFormatter": "biomejs.biome"
+  },
+  "[typescriptreact]": {
+    "editor.defaultFormatter": "biomejs.biome"
+  },
+  "[vue]": {
+    "editor.defaultFormatter": "biomejs.biome"
+  },
+  "[yaml]": {
+    "editor.defaultFormatter": "biomejs.biome"
+  },
+  "editor.codeActionsOnSave": {
+    "source.fixAll.biome": "explicit",
+    "source.organizeImports.biome": "explicit"
+  }
+}