Advanced Paste: categories, resizable window, character counter, drag-and-drop reorder, and expanded pinned item limit

### Description of the new feature / enhancement

Clipboard Manager's pinned items are useful but the current implementation has several UX gaps that limit it for power users who rely on saved snippets as a daily workflow tool.

1. The popup window is a fixed size with no resize handle. On large monitors this wastes screen space and forces unnecessary scrolling through pinned items.

2. Pinned items are a flat, unorganized list. There is no way to group them by category or context, making the tool slow to use when more than a handful of snippets are saved.

3. The pinned item limit appears to be approximately 25. The default is reasonable but there is no way to increase it. Power users with 32GB+ RAM running snippet-heavy workflows would benefit significantly from a user-configurable limit in Settings with no hard ceiling.

4. There is no character count visible on pinned items. Platforms like Facebook enforce strict character limits (e.g. 250 characters for comment replies). Users have no way to verify compliance without pasting elsewhere first.

5. Reordering pinned items requires unpinning and re-pinning in sequence. There is no drag-and-drop reorder within the pinned list.

Proposed solutions:
- Resizable popup window (draggable corners/edges, remembers last size)
- User-defined categories with collapsible sections and tab/sidebar filtering
- User-configurable pinned item limit in Settings (default ~25 is fine, remove the hard ceiling for users who want more)
- Character count badge per pinned item with a user-configurable threshold and warning color when exceeded
- Drag-and-drop reorder within categories, persisted across sessions

### Scenario when this would be used?

Facebook Group administrators managing large communities (10,000+ members) use saved moderation reply snippets dozens of times per day. Facebook enforces a 250-character limit on comment replies, making the character count feature critical — there is currently no way to verify a snippet is within limits without pasting it elsewhere first.

The same workflow applies to customer support teams, social media managers, and anyone using Clipboard Manager as a live snippet library. The flat unorganized list becomes unusable past 8-10 snippets. Categories and drag-and-drop reorder would make this a genuinely powerful tool for high-frequency text workflows.

### Supporting information

PowerToys is widely used by community managers and social media professionals who handle repetitive text workflows. Tools like Beeftext and Ditto already offer categories and unlimited snippets, demonstrating proven demand for these features. Bringing them natively into PowerToys would eliminate the need for a third-party clipboard tool entirely for most users.

Note: this request covers five related UX improvements to the same component rather than filing five separate issues, as they collectively address the same core limitation — Clipboard Manager's current design does not scale for snippet-heavy workflows.

Start by locating the Advanced Paste or Clipboard Manager implementation and reviewing how pinned items, popup sizing, settings, and persistence currently work. Confirm the scope with maintainers before attempting the five related UX changes; done would include categories, resizing, configurable limits, character counts, and drag-and-drop ordering that persist as proposed.

Written by the indexing model from the issue text.