Add Bytehive icons and update trash bin behavior

[guydols]

This pull request introduces a new shared trash-bin management module for deleted files, makes related configuration updates, and adds favicon support across all HTML assets. The most important changes are the addition of the trash.rs module, updates to expose and use its API, and improvements to the user interface with favicons.

Trash-bin management

• Added a new trash.rs module implementing a thread-safe TrashManager for managing deleted files in a shared .bh_filesync/trash/ directory, including moving files to trash, restoring, purging, and listing trash entries. (crates/core/src/trash.rs)
• Exposed TrashEntry and TrashManager types from the core library for use by other modules. (crates/core/src/lib.rs) [1] [2]
• Updated configuration documentation to describe trash behavior and new settings (trash_expiry_days, full_scan_interval_secs). (config.toml)

Frontend/UI improvements

• Added favicon links (bytehive-icon.svg, bytehive_icon_32x32.png) to all HTML assets, ensuring a consistent brand appearance in browser tabs. (crates/core/assets/*.html) [1] [2] [3] [4] [5] [6]
• Added static asset serving and constants for the new PNG favicon images. (crates/core/src/html.rs, crates/core/src/http.rs) [1] [2] [3] [4]

Minor UI/JS style improvements

• Reformatted JavaScript event handlers and conditional logic for better readability in portal.html. (crates/core/assets/portal.html) [1] [2] [3]