Moves Radicle password retrieval to be host-specific, using
1Password to provide different credentials for 'angmar' and 'sidhe',
improving multi-host secret management.

Enhances SSH agent startup to be more robust and XDG-compliant.
The agent is now only spawned if not already running, its socket
is placed in the XDG_RUNTIME_DIR, and its PID is reported upon start.

Sets a default `DFT_BACKGROUND` environment variable.

- Include summary in ABS description
- Add Readeck ID to the end of the ABS description
- Add subcommand to sync listened audiobooks' state as archived articles

Provides `md2html` fish function. This function converts Markdown content
from stdin to an HTML file. It uses `prettier` for formatting, `pandoc`
for conversion, and then opens the generated HTML with `xdg-open`.
Temporary files are stored in `~/Downloads/tmp/responses`.

Adds aliases 'dl', 'ds', and 'df' to facilitate using 'difft' as
the external diff tool for git log, git show, and git diff commands
respectively.

The `base16` syntax theme for `git delta` was causing issues with contrast,
especially on dark terminals. Changed it to `ansi` to improve readability and
ensure better compatibility across different terminal color schemes.

- Add `everforest-dark` and `everforest-light` themes
- Add `config.tmpl` supporting dynamic theme and font selection