feat(ui): expanded thumbnail and preview features (#390)

* Fix text and RAW image handling

- Fix RAW images not being loaded correctly in the preview panel
- Fix trying to read size data from null images
- Refactor `os.stat` to `<Path object>.stat()`
- Remove unnecessary upper/lower conversions
- Improve encoding compatibility beyond UTF-8 when reading text files
- Code cleanup

* Use chardet for character encoding detection

* Add support for waveform + album cover thumbnails

* Rename "cover" variables for MyPy

* Rename "audio_tags" variables for MyPy + typing

* Add # type: ignore to fromstring method

* Add GIF preview support

* Add rough check for invalid video codecs

* Add ".plist" to PLAINTEXT_TYPES

* Add readable video tester

* Add ".psd" to IMAGE_TYPES; Handle ID3NoHeaderError

* Improve and style waveform previews

* Add final return statement to _album_artwork()

* Add final return statement to _audio_waveform()

* Tweak waveform color and size

* Fix ItemThumb label text color in light mode

* Fix most theme UI legibility issues

* Match additional UI to color scheme

* ruff format

* feat(ui): add UI color palette dict

* feat(ui) center and color small font previews

* fix(ui): large font previews follow app theme

* fix(ui): blender previews follow app theme

* feat(ui): add resizable thumbnail options

* fix: mkv files with "[0][0][0][0]" codec load properly

* fix: missing audio files properly handled

* feat(ui): use system accent color for thumb selections

* fix(ui): hide gif preview in multi-selections

* feat(ui): add dynamic file thumb icons

* fix(ui): hide previous thumbnail before resizing

* (fix): catch ffmpeg errors in file tester

* Squashed commit of the following:

commit 9a3c19d398
Author: Travis Abendshien <lvnvtravis@gmail.com>
Date:   Wed Jul 24 22:57:32 2024 -0700

    fix: add missing comma + sort extensions

commit 53b2db9b5f
Author: Travis Abendshien <lvnvtravis@gmail.com>
Date:   Wed Jul 24 14:46:16 2024 -0700

    refactor: move type constants to new media classes

* feat(ui): add media types and icon resources

* feat(ui): add more default media types and icons

Add additional default icons for:
- Blender
- Presentation
- Program
- Spreadsheet
Add/expand additional media types:
- PDF
- Packages

* fix: remove leading dot in preview panel ext

* refactor: remove edge from `four_corner_gradient()`

* fix: handle missing files in `resource_manager`

* fix(ui): thumb edges fading on refresh

* feat(ui): add default icons for audio+vector thumbs

* feat(ui): apply edge to default icon thumbs

* chore: remove unused code

* refactor(ui): move loading icon to `ResourceManager`

* fix(ui) color for default icons follow theme

* fix: remove `theme_color` redef

* refactor: make some consts and args clearer

* refactor: organize arguments, update docstrings

The ability to pass a border radius scaling argument is also included.

* chore: format docstrings with ruff

* refactor: replace magic numbers with named values

* refactor: remove unused code, comments, & imports

* refactor: rename args to not shadow builtins

* refactor: remove unused vars from `thumb_renderer`

* fix: handle ValueError in `render()`

Handle ValueErrors in `render()`. This case was encountered when attempting to render an `XPM` file during testing.

* docs: add FFmpeg requirement to README

README.md

@@ -63,6 +63,8 @@ If you're interested in contributing to TagStudio, please take a look at the [co
 
 To download TagStudio, visit the [Releases](https://github.com/TagStudioDev/TagStudio/releases) section of the GitHub repository and download the latest release for your system under the "Assets" section. TagStudio is available for **Windows**, **macOS** _(Apple Silicon & Intel)_, and **Linux**. Windows and Linux builds are also available in portable versions if you want a more self-contained executable to move around.
 
+For video thumbnails and playback, you'll also need [FFmpeg](https://ffmpeg.org/download.html) installed on your system. 
+
 > [!IMPORTANT]
 > On macOS, you may be met with a message saying _""TagStudio" can't be opened because Apple cannot check it for malicious software."_ If you encounter this, then you'll need to go to the "Settings" app, navigate to "Privacy & Security", and scroll down to a section that says _""TagStudio" was blocked from use because it is not from an identified developer."_ Click the "Open Anyway" button to allow TagStudio to run. You should only have to do this once after downloading the application.