agg: matoleo yote na matoleo ya zamani

This release improves the rendering quality of certain glyph sets and adds the ability to select which frames to render:
- improved box drawing glyphs (light/heavy lines, half-lines, corners, junctions) by using font metric-based strokes
- improved rendering of Powerline symbols in the default (swash) renderer
- fixed the kanagawa-light theme
- added the --select option for frame selection (see below)
Example of box drawing, Powerline, and emoji rendering in 1.9.0:
Frame selection
The new --select <SELECTOR> option allows choosing which part of a recording to render.
It supports both animated excerpts and discrete/slideshow-style selections:
agg --select 5..30 demo.cast clip.gif
agg --select 12.5 demo.cast frame.gif
agg --select marker:build..marker:test demo.cast build.gif
agg --select markers demo.cast markers.gif
A selector can be:
- .. (default), POS.., ..POS, or POS..POS for time ranges
- POS or POS,POS,... for discrete positions
- markers for all marker positions
POS can be a time (12.5, 1m20s, 1:20), a percentage (50%), a marker (marker:build, marker:3), or an event index (event:100). Selection is resolved on the adjusted output timeline, after idle-time limiting and speed adjustment.
Range selections use the normal animated GIF path: visual deduplication, timestamp normalization, and FPS capping. Discrete selections keep every resolved selected position and assign sequential output timestamps using --last-frame-duration.
Example of a "slideshow" GIF generated from demo.cast (from this repo) using the following command:
agg --font-size 20 --select 20%,40%,63%,94% --last-frame-duration 2 demo.cast demo-select.gif

This is a quick follow up release for today's 1.8.0, which addresses a few rendering regressions:
- improved font fallback in the swash renderer: when configured font families don't contain a glyph, agg now tries other loaded system and --font-dir fonts before giving up
- improved font fallback in the resvg renderer to prefer agg's configured fallback chain before falling back to arbitrary fonts from the font database
- fixed clipping/overpainting of glyphs that extend beyond their own terminal cell in the swash renderer
The highlights from 1.8.0:
- added new swash font/text rendering backend, now the default, replacing fontdue; --renderer fontdue remains accepted as a compatibility alias
- improved font fallback, with built-in Noto Emoji and Nerd Font Symbols fallback fonts
- added --text-font-family and --emoji-font-family options for finer control over font selection; --font-family still works as an all-in-one override
- improved rendering of emoji, Nerd Font icons, CJK characters, bold/italic text, underlines, and block/mosaic drawing characters
- added explicit support for Apple Color Emoji on macOS
- added fallback handling for unsupported COLRv1 color emoji glyphs
- added --bold-is-bright option to render bold text using bright ANSI colors
- fixed faint text attribute and underlined spaces rendering in the resvg renderer
- --line-height values below 1.0 are now rejected with a clear error message
- upgraded avt to latest version to bring recent terminal emulation improvements
- upgraded rendering, CLI, HTTP, logging, and Nix-related dependencies
- updated Nix package/development setup

- added new swash font/text rendering backend, now the default, replacing fontdue; --renderer fontdue remains accepted as a compatibility alias
- improved font fallback, with built-in Noto Emoji and Nerd Font Symbols fallback fonts
- added --text-font-family and --emoji-font-family options for finer control over font selection; --font-family still works as an all-in-one override
- improved rendering of emoji, Nerd Font icons, CJK characters, bold/italic text, underlines, and block/mosaic drawing characters
- added explicit support for Apple Color Emoji on macOS
- added fallback handling for unsupported COLRv1 color emoji glyphs
- added --bold-is-bright option to render bold text using bright ANSI colors
- fixed faint text attribute and underlined spaces rendering in the resvg renderer
- --line-height values below 1.0 are now rejected with a clear error message
- upgraded avt to latest version to bring recent terminal emulation improvements
- upgraded rendering, CLI, HTTP, logging, and Nix-related dependencies
- updated Nix package/development setup

- added Kanagawa themes (thanks @Neved4!)
- when conversion fails the output file is now automatically removed (thanks @rcorre!)
- when input recording file has invalid terminal size a friendly error message is now displayed
- improved direct conversion from URL when self-hosted asciinema server is used with S3 file store
- bumped MSRV (minimum supported Rust version) to 1.85
- upgraded dependencies related to font/text rendering
- added --quiet option to hide progress bar
- changed default font size from 14 to 16

- upgraded avt to latest version to bring all recent terminal emulation improvements

- fixed rendering of initial blank frame

- fixed GIF looping
- removed timestamps from log messages