test(navigation): complete unavailable capability matrix

[neusse]

Part of #395.

This is the narrow accounting replacement for cumulative draft #400. The approved Navigation MVP explicitly rejects a public activation tool whose only correct KiCad 10 behavior is unsupported_capability, so this PR does not publish that tool.

Retained value from #400

• Adds separate center_object and fit_view entries to the editor capability model.
• Reports both as unavailable from the bundled KiCad protocol, alongside exact document/sheet activation and reveal.
• Extends the hermetic editor-state test to prove all five unavailable capabilities carry explicit protocol evidence and a reason.

Intentionally excluded

• No activate_editor_context public tool.
• No RunAction, mouse/keyboard, window-order, or selection-implies-reveal fallback.
• No public-tool count or documentation churn.

Evidence

• Focused editor-state capability test — passed
• cargo xtask fix-doc-counts --check — 21 toolsets, 225 registered, 232 total; no changes needed
• cargo fmt --all -- --check — passed
• cargo clippy --workspace --locked --all-targets -- -D warnings — passed
• cargo test --workspace --locked --lib --tests — passed
• cargo test --workspace --locked --doc — passed

Derived from the generally useful capability-model portion of @dubesinhower's #400 / e87914e6; original authorship is preserved.