feat(editor): add multicolor highlight with auto-contrast text (#3110)

* feat(editor): add multicolor highlight with auto-contrast text

Enable the Tiptap Highlight extension in multicolor mode, replacing the
single-color yellow toggle with a full color picker (16 presets + custom).
When the chosen highlight color is perceptually dark, text inside the mark
automatically renders white for readability.

Changes span the full pipeline:
- Editor: ColorPicker UI, extended renderHTML for contrast detection
- PDF: normalizeMarkElements preserves data-color as inline style
- DOCX: mergeStyle reads actual background-color from <mark>
- Utils: new isDarkColor() luminance helper

Backward-compatible: legacy <mark> without data-color still renders yellow.

Resolves #3109

* fix: handle multicolor highlight edge cases

---------

Co-authored-by: Amruth Pillai <im.amruth@gmail.com>

apps/web/locales/en-US.po

@@ -648,6 +648,7 @@ msgstr "Chinese (Traditional)"
 msgid "Choose a model and resume draft."
 msgstr "Choose a model and resume draft."
 
+#. Preset or custom shade refer to the color picker
 #. Preset or custom shade refer to the color picker
 #: src/components/input/rich-input.tsx
 msgid "Choose a preset or custom shade."
@@ -665,6 +666,7 @@ msgstr "Choose an existing conversation from the sidebar, or start a new draft-f
 msgid "Circle"
 msgstr "Circle"
 
+#. Clear the highlight color
 #. Clear the text color
 #: src/components/input/rich-input.tsx
 msgid "Clear"
@@ -1774,6 +1776,10 @@ msgstr "High"
 msgid "Highlight"
 msgstr "Highlight"
 
+#: src/components/input/rich-input.tsx
+msgid "Highlight Color"
+msgstr "Highlight Color"
+
 #: src/libs/locale.ts
 msgid "Hindi"
 msgstr "Hindi"
@@ -1803,7 +1809,6 @@ 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"