Split Lit Blog into general announcement with CLI tutorial and deep dive

[hannahhoward]

What

Split the existing Lit blog draft into two separate posts:

1. A general announcement and simple tutorial that shows how to do encryption via the CLI
2. A deep dive on how our encryption/decryption via Lit actually works.

Why

#316 is great work but quite complicated for beginners without a lot of context on Lit and Storacha.

For our main blog announcement, I think it's important we keep it simple and accessible, with a link to a seperate deep dive on how Lit & Storacha work together under the hood. The simple and accessible version will also make more sense for publishing on Lit's side.

Proposal

Once storacha/upload-service#175 & storacha/upload-service#176 are done, extract the introductory language and pair with a tutorial on how to implement encrypt & decrypt via the CLI. Maybe use the Lit Partner Contribution Template as a general guide: https://docs.google.com/document/d/1slDD6ZFPxwyh54m8aehBpB3XT0r4P4h2ppDbCwR08GA/edit?tab=t.0#heading=h.okv21jgifxa3

Take the existing content from #316 on the underlying technicals and make a deep dive post -- we can link it from the original post as needed.