Add Transparent Pixel Support and Minor Fixes.

[Stattek]

Adds ability to render PNGs with transparent pixels (pixels that are at least 95% transparent will be rendered with 0 index in charset).

• Update image to version 0.25.5
• Run cargo fmt on src files.
• Add new option to allow ANSI codes to be generated per character rather than when the color has changed, to make it easier to parse by other programs.
• Add new charset that gives similar output to jp2a program.
• Change default image output to 128 from 80, to be accurate with documentation.
• Update readme.

Summary by Sourcery

New Features:

• Support transparent pixels in PNG images, rendering pixels with at least 95% transparency with the minimum index in the charset.

[sourcery-ai]

Reviewer's Guide by Sourcery

This pull request introduces transparent pixel support and a new option for escaping ANSI color codes on each character. The changes include updates to the rendering logic, command-line options, charsets, and dependency versions, along with code formatting improvements.

Updated Class Diagram for ImageRenderer and RenderOptions

classDiagram
    class ImageRenderer {
      - resource: &DynamicImage
      - options: RenderOptions
      + get_char_for_pixel(pixel: Rgba<u8>, maximum: f64): &str
      + get_opacity_percent(pixel: Rgba<u8>): f64
      + get_grayscale(pixel: Rgba<u8>): f64
    }

    class RenderOptions {
      - width: Option<u32>
      - height: Option<u32>
      - colored: bool
      - escape_each_colored_char: bool
      - invert: bool
      - charset: &[&str]
      + escape_each_colored_char(escape: bool): Self
      + invert(invert: bool): Self
      + ...
    }

    ImageRenderer --> RenderOptions : uses

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File-Level Changes

Change	Details	Files
Implement transparent pixel rendering logic	Added a new method to compute pixel opacity Modified character selection to handle pixels with less than 95% opacity as transparent Updated inline documentation for transparency handling	src/image_renderer.rs
Add option for per-character ANSI escape codes	Introduced a new command-line flag for escaping each colored character individually Added a boolean field and a builder method in RenderOptions Adjusted rendering logic to check for the new flag when writing ANSI codes	src/main.rs src/renderer.rs src/image_renderer.rs
Update default image output width	Changed the default width from 80 to 128 to align with documentation	src/main.rs
Update dependency and formatting	Bumped the image crate version from 0.24.6 to 0.25.5 Ran cargo fmt on source files to standardize formatting Updated Cargo.lock accordingly Added a new (empty) gif_renderer module	Cargo.toml Cargo.lock src/gif_renderer.rs
Enhance charset support	Added a new charset definition ('minimal') to provide a different rendering style Updated charset mappings in the charset module	src/charsets.rs
Update documentation	Documented the new escape-each-char option in README.md Clarified the default behavior for colored output	README.md

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[sourcery-ai]

Hey @Stattek - I've reviewed your changes - here's some feedback:

Overall Comments:

• Extract the 0.95 opacity threshold into a named constant to make its purpose clearer.
• Abstract the repeated ANSI color prefix logic into a helper function to reduce duplication between writer and buffer handling.

Here's what I looked at during the review

• 🟡 General issues: 2 issues found
• 🟢 Security: all looks good
• 🟢 Testing: all looks good
• 🟢 Complexity: all looks good
• 🟢 Documentation: all looks good

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[orhnk]

using u8::MAX is smarter than plain 255.

Just a note to myself

[orhnk]

Thank you for your PR. I'm waiting for the question