feat: add section heading icons to PDF templates (#3127)

* feat: add section heading icons to PDF templates

Add customizable Phosphor icons before section titles in PDF output.
Users can toggle visibility globally via a new "Hide section heading icons"
switch (independent of item-level icons) and customize individual section
icons through the builder sidebar icon picker.

- Add `icon` field to `baseSectionSchema` and `summarySchema`
- Add `hideSectionIcons` to `pageSchema` (defaults to true for backward compat)
- Implement `SectionHeadingIcon` component with heading font-size scaling
- Support "none" sentinel for per-section icon hiding
- Fallback to sensible defaults (briefcase, graduation-cap, etc.) for legacy data
- Add icon picker to builder sidebar sections and custom section dialogs

Closes #2632

* test: add unit tests for section heading icons

- Add tests for getResumeSectionIcon() covering built-in sections,
  summary, custom sections, "none" sentinel, and default fallbacks
- Add schema tests for baseSectionSchema icon field, summarySchema icon,
  and pageSchema hideSectionIcons default behavior

* refactor: minor updates to icon display

* Update apps/web/locales/es-ES.po

Co-authored-by: coderabbitai[bot] <136622811+coderabbitai[bot]@users.noreply.github.com>

---------

Co-authored-by: Amruth Pillai <im.amruth@gmail.com>
Co-authored-by: coderabbitai[bot] <136622811+coderabbitai[bot]@users.noreply.github.com>

packages/pdf/src/templates/shared/primitives.test.ts

@@ -0,0 +1,13 @@
+import { readFileSync } from "node:fs";
+import { fileURLToPath } from "node:url";
+import { describe, expect, it } from "vitest";
+
+const source = readFileSync(fileURLToPath(new URL("./primitives.tsx", import.meta.url)), "utf8");
+
+describe("SectionHeadingIcon", () => {
+	it("passes the resolved heading icon size through the icon size prop", () => {
+		expect(source).toContain("size: sizeProp");
+		expect(source).toContain("{...(resolvedSize === undefined ? {} : { size: resolvedSize })}");
+		expect(source).not.toContain("{ size: headingFontSize } as Style");
+	});
+});