Add an export button to the ontology sidebar for the existing Turtle endpoint

[Schro-code]

Why

GET /kbs/{id}/export exports the whole knowledge base (every fact with its provenance), not just the ontology. An "Export" button on the Ontology page promises the wrong thing.

What changes

• Removed the export button from the Ontology sidebar.
• Added an "Export knowledge base (RDF)" card to KbSettings under the General section, where it sits alongside other knowledge-base-level actions.
• i18n strings updated in both en.ts and zh.ts: "Export knowledge base (RDF)" / "导出整个知识库（RDF）".

How it was checked

• Verified pnpm build passes (type-checks the new strings and imports).

Before review

• Every commit is signed off (git commit -s)
• cargo fmt --all --check, cargo clippy --workspace --all-targets -- -D warnings and cargo test --workspace pass — N/A, no Rust changes
• For changes under web/: pnpm build and pnpm test pass — yes
• SQL under crates/utopia-store/ — N/A
• A new migration — N/A
• UI strings are in both web/src/i18n/en.ts and zh.ts
• A change to the data model — N/A

[WaylandYang]

Thank you for this.

One change: GET /kbs/{id}/export exports the whole knowledge base (every fact with its provenance), not the ontology, so an "Export" next to the ontology's Import promises the wrong thing. Could the button say "Export knowledge base (RDF)" / "导出整个知识库（RDF）" and move to the base's settings (KbSettings)?

Thanks again.

[Schro-code]

Perfect — moved the button to KbSettings and renamed it to "Export knowledge base (RDF)" / "导出整个知识库（RDF）". The ontology sidebar no longer has it.

Thanks