Add Obsidian Toolbox — 4 syntax generators under /tools

Inside-LMS toolbox for registered students: callout-CSS, YAML-frontmatter,
theme CSS-variables, Style Settings generators. Auth inherited from (student)
route group; no public surface, no email gate.

- Pure generators in src/lib/tools/* with Vitest (33 tests)
- Shared YAML-safe scalar quoter (_shared/yaml.ts) used by frontmatter +
  style-settings: unquoted user input was silently breaking YAML (tags '#x'
  -> null, color default '#7C3AED' -> null, 'a: b' -> parse error)
- hex validation in callout (no NaN), date input constrained, clipboard +
  analytics calls guarded
- Prisma ToolUsage model + migration; logToolUsage Server Action (auth-first,
  10-min dedup window per user/tool)
- Tool index /tools + ToolCard (explicit lucide map, no import *) + header link

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

src/lib/tools/__tests__/callout.test.ts

@@ -0,0 +1,35 @@
+import { describe, it, expect } from "vitest";
+import { buildCalloutCss, normalizeCalloutId } from "@/lib/tools/callout";
+
+describe("normalizeCalloutId", () => {
+  it("слагифицирует пробелы и регистр", () => {
+    expect(normalizeCalloutId("My Note ")).toBe("my-note");
+  });
+  it("выкидывает недопустимые символы", () => {
+    expect(normalizeCalloutId("Идея!@# 2")).toBe("2");
+  });
+});
+
+describe("buildCalloutCss", () => {
+  it("генерирует css с data-callout и rgb", () => {
+    const r = buildCalloutCss({ id: "idea", title: "Идея", color: "#7C3AED", icon: "lightbulb" });
+    expect(r.css).toContain('[data-callout="idea"]');
+    expect(r.css).toContain("--callout-color: 124, 58, 237;");
+    expect(r.css).toContain("--callout-icon: lucide-lightbulb;");
+  });
+  it("поддерживает короткий hex", () => {
+    const r = buildCalloutCss({ id: "x", title: "X", color: "#fff", icon: "star" });
+    expect(r.css).toContain("--callout-color: 255, 255, 255;");
+  });
+  it("кидает на пустом id", () => {
+    expect(() => buildCalloutCss({ id: "!!!", title: "", color: "#000", icon: "x" })).toThrow();
+  });
+  it("markdown содержит [!id]", () => {
+    const r = buildCalloutCss({ id: "warn", title: "Внимание", color: "#f00", icon: "alert" });
+    expect(r.markdown).toContain("> [!warn] Внимание");
+  });
+  it("кидает на некорректном HEX (не отдаёт NaN)", () => {
+    expect(() => buildCalloutCss({ id: "x", title: "X", color: "#zz", icon: "star" })).toThrow();
+    expect(() => buildCalloutCss({ id: "x", title: "X", color: "#1234", icon: "star" })).toThrow();
+  });
+});