feat(presets): add pdflatex, tectonic, asciidoctor, and quarto presets (#30)

* feat(presets): add pdflatex preset

Adds a direct pdflatex preset for users who want single-pass
compilation without latexmk orchestration. Uses -file-line-error
for parseable diagnostics and reuses the existing parse_latexmk
error parser since both emit the same file:line: message format.

* feat(presets): add tectonic preset

Adds a tectonic preset for the modern Rust-based LaTeX engine, which
auto-downloads packages and requires no TeX installation. Reuses
parse_latexmk since tectonic emits the same file:line: message
diagnostic format.

* feat(presets): add asciidoctor preset

Adds an asciidoctor preset for AsciiDoc → HTML compilation with SSE
live-reload. Includes a parse_asciidoctor error parser handling the
"asciidoctor: SEVERITY: file: line N: message" format for both
ERROR and WARNING diagnostics.

* feat(presets): add quarto preset

Adds a quarto preset for .qmd scientific documents rendering to
self-contained HTML with SSE live-reload. Uses --embed-resources
to avoid a _files directory in the common case. No error_parser
since quarto errors are heterogeneous (mixed R/Python/pandoc output).

* refactor: apply stylua formatting to new preset code

doc/preview.nvim.txt

@@ -157,8 +157,12 @@ Import them from `preview.presets`:
 
   `presets.typst`              typst compile → PDF
   `presets.latex`              latexmk -pdf → PDF (with clean support)
+  `presets.pdflatex`           pdflatex → PDF (single pass, no latexmk)
+  `presets.tectonic`           tectonic → PDF (Rust-based LaTeX engine)
   `presets.markdown`           pandoc → HTML (standalone, embedded)
   `presets.github`             pandoc → HTML (GitHub-styled, `-f gfm` input)
+  `presets.asciidoctor`        asciidoctor → HTML (AsciiDoc with SSE reload)
+  `presets.quarto`             quarto render → HTML (scientific publishing)
 
 Enable presets with `preset_name = true`:
 >lua