feat(dates): allow configurable default timezone

docs/plugins/CreatedModifiedDate.md

@@ -12,6 +12,7 @@ This plugin determines the created, modified, and published dates for a document
 This plugin accepts the following configuration options:
 
 - `priority`: The data sources to consult for date information. Highest priority first. Possible values are `"frontmatter"`, `"git"`, and `"filesystem"`. Defaults to `["frontmatter", "git", "filesystem"]`.
+- `timezone`: The timezone that is assumed (IANA format, e.g. `Africa/Abidjan`) when one is not specified in the datetime frontmatter properties. Defaults to `system`: the system's local timezone.
 
 > [!warning]
 > If you rely on `git` for dates, make sure `defaultDateType` is set to `modified` in `quartz.config.ts`.

quartz/plugins/transformers/lastmod.ts

@@ -4,13 +4,21 @@ import { DateTime, DateTimeOptions } from "luxon"
 import { Repository } from "@napi-rs/simple-git"
 import { QuartzTransformerPlugin } from "../types"
 import chalk from "chalk"
+import { Settings as LuxonSettings } from "luxon/src/settings"
 
 export interface Options {
   priority: ("frontmatter" | "git" | "filesystem")[]
+  /**
+   * The default timezone when handling dates.
+   * Valid options are "system" (default), "utc", an IANA string, or a UTC offset
+   * https://moment.github.io/luxon/#/zones?id=specifying-a-zone
+   */
+  timezone: "system" | string
 }
 
 const defaultOptions: Options = {
   priority: ["frontmatter", "git", "filesystem"],
+  timezone: "system",
 }
 
 function parseDateString(fp: string, d: string | number | unknown): DateTime<true> | undefined {
@@ -51,6 +59,8 @@ function parseDateString(fp: string, d: string | number | unknown): DateTime<tru
 
 export const CreatedModifiedDate: QuartzTransformerPlugin<Partial<Options>> = (userOpts) => {
   const opts = { ...defaultOptions, ...userOpts }
+  // note that this will affect the behavior of Luxon globally
+  LuxonSettings.defaultZone = opts.timezone
   return {
     name: "CreatedModifiedDate",
     markdownPlugins() {