feat: add archiving of platform media files (#1)

* chore: specify non-ignored `.md` files

* refactor: rename youtube downloader to ytdlp

More generic name since yt-dlp supports many sites beyond YouTube.

* feat: add local file downloader

Supports file:// URLs for archiving local files.

* deps: add regex crate for URL pattern matching

* feat: expand source detection with granular YouTube types

- Split Source::YouTube into YouTubeVideo, YouTubePlaylist, YouTubeChannel
- Add Source::X for Twitter/X posts
- Add Source::Local for file:// URLs
- Add regex-based URL pattern matching for YouTube URLs
- Add shorthand schemes (yt:video/ID, youtube:playlist/ID, etc.)
- Add comprehensive tests for all URL patterns

* docs: update README milestones

Mark YouTube videos, Twitter videos, and local files as done.

* chore: update flake.lock

* feat: add shorthand schemes for X/Twitter media

* chore: move docs into docs dir

* Remove temp file using timestamp path

Delete the temp entry at store_path/temp/<timestamp> in both
the hash-exists and success paths. Stop constructing the full filename
with extension and remove the early process::exit to de-duplicate
cleanup.

* Add Nix caches and default flake package

* Add social platform source detection and update milestones

* Tighten social URL matching to avoid false positives

* Mark media archiving milestone complete

README.md

@@ -1,52 +0,0 @@
-# archivr
-
-An open-source self-hosted archiving solution. Work in progress.
-
-## Milestones
-- [ ] Archiving
-    - [ ] Archiving media files from social media platforms
-        - [ ] YouTube
-        - [ ] Twitter
-        - [ ] Instagram
-        - [ ] Facebook
-        - [ ] TikTok
-        - [ ] Reddit
-        - [ ] Snapchat
-        - (Some of these could be postponed for later.)
-    - [ ] Archiving local files
-        - [ ] Archive videos (MP4, WebM)
-        - [ ] Archive audio files (MP3, WAV)
-        - [ ] Archive documents (DOCX, XLSX, PPTX)
-        - [ ] Archive PDFs
-        - [ ] Archive images (JPEG, PNG, GIF)
-    - [ ] Archiving files from cloud storage services (Google Drive, Dropbox, OneDrive) and from URLs
-        - [ ] URLs
-        - [ ] Google Drive
-        - [ ] Dropbox
-        - [ ] OneDrive
-    - [ ] Archive web pages (HTML, CSS, JS, images)
-    - [ ] Archiving emails (???)
-        - [ ] Gmail
-        - [ ] Outlook
-        - [ ] Yahoo Mail
-- [ ] Management
-    - [ ] Deduplication
-    - [ ] Tagging system
-    - [ ] Search functionality
-    - [ ] Categorization
-    - [ ] Metadata extraction and storage
-- [ ] User Interface
-    - [ ] Web-based UI
-- [ ] Backup and Sync
-    - [ ] Cloud backup (AWS S3, Google Cloud Storage)
-    - [ ] Local backup
-
-## Motivation
-There are two driving factors behind this project:
-- In the age of information, all data is ephemeral. Social media platforms frequently delete content, and cloud storage services can become inaccessible and unreliable. Being able to archive important data is *very important* for preserving personal memories and digital history.
-- I will be creating a small encyclopedia for my future family and kids. Therefore, I want to make sure that all the information I gather is preserved and accessible for future reference.
-
-This project aims to provide a reliable solution for archiving important data from various sources, ensuring that users can preserve their digital assets for the long term.
-
-## License
-This project is licensed under the MIT License. See the [LICENSE](LICENSE.md) file for details.