docs(get-started): rewrite the introduction in Simplified Technical English (#120) #122

Context

Deferred from #120, which is closed. #121 fixed the eight other acceptance criteria of that
review and landed on staging as 56cab1b. This one remains, and it is not a false published
claim, so it does not block the v0.1.0 tag.

The finding, as #120 stated it

src/content/docs/get-started/index.md:10-20 uses long sentences, fragments, metaphors ("the
citation becomes the doorway"), and ambiguous claims such as "No central host."

The page is the front door of the site. A reader who does not read English as a first language
meets it first, and a translator meets it next. The prose is written for effect rather than for
transfer.

The unconditional persistence claim in the same paragraph is already fixed in 56cab1b: the
sentence now reads "permanent once the record is active". Only the style question is open.

What to do

1. Replace the opening with short, literal statements. review: address PR #4 clarity and minimalism findings before v0.1.0 #120 proposed this shape:

   TextRefs assigns a URI to a passage. It does not host text or replace editions. It links the
   passage to editions, identifiers, and resolver URLs. Only active records have a persistence
   guarantee.

2. Define the four record types in a table or a short list.

3. Keep every fact the current page states. This is a rewrite for style, not a cut of scope.

4. Apply the same pass to the de translation of the page, so the pair does not drift.

Acceptance criteria

• The get-started introduction uses short, literal, status-accurate sentences.
• Each instruction sentence is under 20 words, and each descriptive sentence is under 25.
• The four record types appear as a table or a short list.
• No metaphor stands in for a technical statement.
• npm run verify passes.

Related: #4, #120, #121.