Keep the router out of the embeddable diagram (#356)

[adamjohnwright]

Part of #356: the embed should cost under a third of what the site's Pathway Browser costs for the same diagram.

Cause. The embed never routes, but it carried @angular/router (67 KB).

• Everything that draws a pathway injects UrlStateService, and that class, the injection token itself, imported the Router to keep state in the address bar.
• The embed's MemoryState also imported from that file.
• diagram.component and species.service injected Router/ActivatedRoute optionally, which still imports them.

Change

• UrlStateService is now an abstract, router-free base. It holds the state signals (built by createStateValues, as before), the tab maps and the dbId lookup. section, settle, navigateTo and two new members are abstract. It imports only router types.
• RouterUrlStateService (router-url-state.service.ts) is the address-bar implementation. It's moved unchanged, except that the shared parts now come from the base. The site provides it in src/app/app.config.ts, replacing providedIn: 'root'.
• MemoryState extends the base, so its copy of every field is gone.
• The last direct router reads are now state.isFirstNavigation() (the diagram's first-load check) and state.queryParams() (the species switch). The embed answers true and {}, which is what it got before, with no router injected.
• lodash isArray/isNumber in the state service are now Array.isArray and typeof.
• The detail page's DetailUrlState (a Partial of the state) is unaffected. Nothing on that page calls the two new members: its diagram is an image component, not cr-diagram.

Size. The embed's initial JavaScript goes from 1.58 MB to 1.50 MB (all its JavaScript: 1,650 KB to 1,570 KB). @angular/router is at 0 bytes in the stats.

Checks

• Unit tests: 723 passed. entity.service.spec now provides the state itself, because it's no longer provided at the root automatically.
• Full e2e suite locally: 401 passed, 6 skipped.
• Preflight passes. Lint and dead code are unchanged.

Next for #356

• lodash: cytoscape-style: drop lodash for small local memoize and throttle ngx-reactome-base#15 (merged) removes it from the style library, and a follow-up here updates that dependency.
• Then fcose, loaded only when needed.

🤖 Generated with Claude Code

[adamjohnwright]

Review (subagent, adversarial): no defects. The moved class is line-for-line the old one (bar Array.isArray, a type rename and Boolean(!x) -> !x); field order under useDefineForClassFields: false is safe (route before section, no base initialiser touches subclass fields); every injector resolves (site via app.config, embed via MemoryState/rootGuards, detail page its own provider, specs updated); isFirstNavigation/queryParams read the same root Router/ActivatedRoute as before; the embed stats show no @angular/router. Nits fixed in the latest commits: queryParams() returns a copy rather than the router's object, a stale comment above the removed Router injection is gone, and DetailUrlState now says plainly that it is a Partial, so nothing checks it has settle/navigateTo/isFirstNavigation/queryParams -- nothing on the content pages calls them.