Add support for Tumblr to Flare

Hi! First of all, thank you for your work on Flare. It has been a very useful project, and I appreciate the effort that has gone into building and maintaining it.
I would like to suggest adding support for Tumblr!! (https://www.tumblr.com/)

Motivation
Tumblr remains an active platform with a strong presence in art, fandom, and long-form visual blogging communities. Supporting Tumblr could:
Expand Flare’s compatibility with a broader range of social/content platforms
Attract users who are active outside mainstream networks like Twitter or Reddit
Improve overall utility for users who aggregate or interact across multiple platforms

Proposed Scope
Initial support could focus on:
Basic post detection (text, image, and link posts)
Parsing post metadata (author, timestamp, tags)
Compatibility with Tumblr post URLs and embeds

Feasibility Considerations
From a technical perspective, this seems feasible for several reasons:

Consistent Page Structure
Tumblr posts typically follow a relatively stable DOM structure, especially for public posts.

Public Accessibility
Most Tumblr content is publicly accessible without authentication, which simplifies integration.

API Availability (Optional)
Tumblr provides an API that could be used for structured data retrieval if needed, though initial support could rely on DOM parsing.

Similarity to Existing Platforms
If Flare already supports platforms with similar post-based structures (e.g., feeds with media + metadata), Tumblr integration could reuse parts of the existing parsing logic.

Potential Challenges
Variability across themes (custom Tumblr themes may affect DOM structure)

Handling NSFW or restricted content gracefully

Pagination and infinite scrolling behavior

Closing
I believe Tumblr support would be a valuable addition to Flare and align well with its current capabilities.

Thank you for considering this suggestion！

The issue names no files, tests, or entry points; start by comparing existing platform integrations in Flare. Done means Tumblr text, image, and link posts expose author, timestamp, tags, URLs, and embeds, with the listed access and content cases handled.