[Registry Preview] Support metadata directives in .reg comments

### Description of the new feature / enhancement

Registry Preview already parses .reg files before import. It could recognize
optional metadata stored in comment lines, such as `;Title=`, `;Description=`,
`;Author=` and `;Requires=`, and display this information to the user before/after import.

Example:

```
Windows Registry Editor Version 5.00

;Title=Example Tweak
;Description=A short human-readable description of what this .reg file does.
;Requires=ExplorerRestart
;Author=John Doe

[HKEY_CURRENT_USER\Software\Classes\CLSID\...]
<...>
```

Registry Preview could display something like:

- Title: Example Tweak
- Description: A short human-readable description of what this .reg file does.
- Additional action required after import: Restart Windows Explorer

Supported Requires values (initial set):
```
;Requires=ExplorerRestart
;Requires=Restart
;Requires=Logoff
```

Unknown `;Key=Value` directives would be silently ignored, so the set can grow later without breaking older files. This is entirely optional - files without this metadata continue to work exactly as they do today.

### Scenario when this would be used?

.reg files are commonly shared on forums, in guides, and between admins/power users. Comments (;) have existed in the .reg format for decades, but they have no dedicated UI surface - Registry Preview currently shows them only as raw text in the left-hand text panel, alongside the rest of the file content, competing for attention with the actual registry syntax. Most users focus on the right-hand tree view, which shows structure but not comments at all.

Someone double-clicking a .reg file never sees the text content, and even users who do open Registry Preview tend to skim the raw text panel rather than read it closely - it reads as "technical detail," not as user-facing
information.

Surfacing recognized metadata (Title/Description/Requires) in a dedicated, prominent panel - rather than leaving it buried in the raw text - would make this context something users actually see and act on, not just something that's technically present in the file.

### Supporting information

100% backward compatible — no changes to the .reg file format, existing Regedit versions already ignore comment lines.

Possible implementation: parse lines matching `;Key=Value` before the first
`[Section]`, store as a metadata dictionary, render in a collapsible info
panel above/alongside the tree view.

Start by locating the Registry Preview entry points for .reg parsing and the right-hand tree-view UI. Check how comment lines are currently handled, then determine where recognized metadata and the Requires actions would fit in a collapsible panel. Done means optional directives are surfaced without changing behavior for files that lack them.

Written by the indexing model from the issue text.