A new base starts with no ontology pack

[WaylandYang]

Closes #580.

A new base starts with no ontology. Nothing is pre-selected in the creation dialog, the General base made at registration installs no pack, and the General base the web app creates for an empty workspace passes an empty list. The five packs stay where they were, one click away.

Why

schema.org was the default on the argument of #322: without domain and range a fact has no direction. The comparison on #580 (same 15 ai-timeline documents, DeepSeek-V3.2, auto_extend_ontology on, bootstrap allowed to finish) says the pack gives types, not predicates:

	no pack	schema.org
entity-to-entity edges with a predicate	56%	49%
entities typed · type accuracy (Wikidata sheet)	80% · 77%	98% · 90%
ontology after bootstrap	13 classes, 175 relations, the corpus's own words	915 classes, 1671 relations
tokens per extraction call	~2k	~18k (the retrieved slice; the full list would be ~105k and never goes in)
extraction drops	346	876, of which 342 domain_mismatch

Leaving the pack out costs ten points of type accuracy on this corpus and buys an ontology the base grows itself, more directed edges, and a ninth of the prompt. Still unmeasured: edges in the empty base that run backwards, which the direction check cannot catch without signatures.

What changed

• auth_routes::register: no install_packs on the General base; the comment says why and points at the measurement.
• kbs.rs: DEFAULT_PACK is gone; install_packs installs what the request names.
• web/src/api.ts: DEFAULT_ONTOLOGY_PACKS is gone; kb.tsx creates General with [], MyKbs.tsx starts the dialog with nothing checked.
• The "None" hint in the pack picker no longer promises "ten seed relations" (there are none since 0009); it says the ontology grows out of the documents.
• docs/pipeline.md and record 0008 (status line, a dated revision with the numbers, the index row).

No migration; existing bases keep what they have.

Checked

cargo fmt, cargo clippy -p utopia-server -D warnings; pnpm test, pnpm build.

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