Add conversion/validation status indicators to User Rules Editor

## Summary

In the User Rules Editor, users can enter rules in any adblock syntax (AdGuard, uBlock, Adblock Plus, etc.). In some cases, these rules need to be converted internally to AdGuard syntax. This conversion is not always possible or may partially succeed. Currently, users have no visibility into whether their rule was converted, how it changed, or whether the rule is invalid.

## Request

Add small status indicators (icons) next to each rule in the User Rules Editor to clearly show:
1. Rule was converted — The rule required syntax conversion to AdGuard format
2. Conversion failed or partially succeeded — Rule was modified but contains issues
3. Rule is invalid — Parsing or validation error
4. Hover tooltip — Tooltip should show the converted rule or the validation error message

### Proposed UI behavior

- Display a small icon next to each rule:
- ⚠️ or 🔄 for converted rules
- ❌ for invalid rules
- On hover:
- Show a tooltip with:
- The converted rule for successful conversions
- The error message for invalid rules or failed conversions

### Motivation

- Improves transparency: users understand how their rules are processed internally
- Helps debugging: users can immediately see whether a rule was accepted or converted
- Enhances UX: reduces confusion around why a rule behaves differently after saving
- Aligns the editor with behavior in other AdGuard tools that show rule diagnostics

### Notes

- Conversion/validation info is already available internally — this feature mainly adds UI presentation.
- Icons should be unobtrusive but clearly visible.
- Later, this could evolve into a more advanced rule diagnostics panel.