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>

apps/web/locales/en-US.po

@@ -1740,8 +1740,8 @@ msgid "Hide"
 msgstr "Hide"
 
 #: src/routes/builder/$resumeId/-sidebar/right/sections/page.tsx
-msgid "Hide all icons on the resume"
-msgstr "Hide all icons on the resume"
+msgid "Hide Icons"
+msgstr "Hide Icons"
 
 #. Accessible label for button that hides password in registration form
 #. Accessible label for button that hides password in reset-password form
@@ -1761,6 +1761,10 @@ msgstr "Hide all icons on the resume"
 msgid "Hide password"
 msgstr "Hide password"
 
+#: src/routes/builder/$resumeId/-sidebar/right/sections/page.tsx
+msgid "Hide Section Icons"
+msgstr "Hide Section Icons"
+
 #. Impact severity label in resume analysis suggestion card
 #: src/routes/builder/$resumeId/-sidebar/right/sections/resume-analysis.tsx
 msgid "High"
@@ -1799,6 +1803,7 @@ msgid "Hungarian"
 msgstr "Hungarian"
 
 #: src/components/level/combobox.tsx
+#: src/dialogs/resume/sections/custom.tsx
 #: src/routes/builder/$resumeId/-sidebar/right/sections/design.tsx
 msgid "Icon"
 msgstr "Icon"