feat: Add educational hint to favorites empty state (#8559)

## Summary

Adds an educational hint to the favorites empty state to teach users how
to favorite inputs.

## Changes

- Add new i18n key `favoritesNoneHint` with text "In the Parameters tab,
click ⋮ on any input to add it here"
- Update empty state template to show hint below the existing
description
- Hint is hidden during search to avoid redundant messaging

## Before/After

**Before:** "Inputs you favorite will show up here"

**After:**
- "Inputs you favorite will show up here"
- "In the Parameters tab, click ⋮ on any input to add it here*

## Context

Per Slack discussion, uses in-app education only (no external docs link)
to ensure text matches the user's specific version of the feature.

Fixes #2fa6d73d

┆Issue is synchronized with this [Notion
page](https://www.notion.so/PR-8559-feat-Add-educational-hint-to-favorites-empty-state-2fc6d73d365081f5827dfafcc1ece95c)
by [Unito](https://www.unito.io)


<!-- This is an auto-generated comment: release notes by coderabbit.ai
-->
## Summary by CodeRabbit

* **New Features**
* Improved empty state in the Parameters panel: message is now two
paragraphs and shows an additional hint (with an icon) when not
searching.
* **Localization**
* Added a new localized hint that explains how to add inputs to
favorites, shown in the Parameters panel empty state.
<!-- end of auto-generated comment: release notes by coderabbit.ai -->

---------

Co-authored-by: Amp <amp@ampcode.com>
Co-authored-by: Rizumu Ayaka <rizumu@ayaka.moe>

src/locales/en/main.json

@@ -2837,6 +2837,7 @@
     "groupSettings": "Group Settings",
     "groups": "Groups",
     "favoritesNoneDesc": "Inputs you favorite will show up here",
+    "favoritesNoneHint": "In the Parameters tab, click {moreIcon} on any input to add it here",
     "noneSearchDesc": "No items match your search",
     "nodesNoneDesc": "NO NODES",
     "fallbackGroupTitle": "Group",