feat(templates): client-Java service starters and a Harmonia page starter (#6582)

[delchev]

Closes #6582. Part of the umbrella #6591 (one application stack: Harmonia UI + client Java).

What changes

Starter	Was	Is
Hello World	service.mjs — response.println	@Controller + @Get returning the greeting
TypeScript (API) → Java (API)	service.ts — response + security/user	sdk.http.{Controller,Get} + sdk.security.User, returning a record (serialized to JSON)
Database Access (API)	service.mjs — db/query	sdk.db.Database.query against SystemDB
HTTP Client (API)	service.mjs — http/client	sdk.http.HttpClient
Data Tables (UI)	AngularJS page (ng-app, blimpKit, platform-links)	standalone Harmonia page — platform webjars, a fetch call, x-h-table, no build step
React starter	React/TSX project	removed — a second UI stack has no counterpart in a one-stack platform

The Java starters follow the job/listener/websocket starters migrated in #6581: generated into
{{javaPackageName}}/{{javaClassName}}.java with a package-qualified @Component bean name, so two
projects can scaffold the same service without colliding in the shared client container.

template-typescript loses its TypeScript-logo template.svg (it would misrepresent a Java starter)
and uses the sap-icon--source-code glyph instead; the module directories and registered orders are
unchanged, so the New-project menu keeps its shape.

A platform bug this surfaced

HttpClientFacade.parseOptions returned null for a null options document while all seven facade
methods (plus their async twins) dereference the result immediately, so the SDK's no-options overload
HttpClient.get(url) failed with an NPE instead of performing the request — the JavaScript API never
hit it because it always sends an options object. Fixed in api-http with unit tests
(HttpClientFacadeTest); it is the second commit here because the migrated starter is what found it.

Verification (running instance, all five scaffolded through the real generation endpoint, published)

• GET /services/java/demohello/demohello/Greeter → Hello World!
• GET /services/java/demoapi/demoapi/Api → {"message":"Hello World","user":"admin","date":…}
• GET /services/java/demodb/demodb/DbAccess → the DIRIGIBLE_EXTENSIONS result set as JSON
• GET /services/java/demohttp/demohttp/Fetcher → the remote response ("statusCode": 200) — 500 before the api-http fix
• the Harmonia page renders in Chrome: toolbar x-h-select, Lucide icon, live table; switching the
  collection re-fetches and re-columns; clean console
• Problems view clean for every scaffolded project; template list shows "Java (API)", no React entry
• mvn -T 1C clean package -P quick-build green

🤖 Generated with Claude Code