feat(server,app,website): prefix service URLs with project slug

Service hostnames now follow DNS convention with a project label so
independently opened projects no longer collide on routes like
`web.localhost`. Format becomes `{script}.{project}.localhost` for
default branches and `{script}.{branch}.{project}.localhost` for other
branches. The project slug comes from the GitHub repository name when a
remote exists, otherwise from the workspace directory basename.

Server changes:
- `buildScriptHostname` takes `{ projectSlug, branchName, scriptName }`
  and slugifies all labels at the boundary; `untitled` fallback only
  applies at hostname-label sites, never to shared `slugify`.
- `deriveProjectSlug(cwd)` and `parseGitHubRepoNameFromRemote` derive
  the slug; GitHub URL parsing now requires `host === "github.com"` to
  avoid embedded-path false matches.
- `ScriptRouteEntry` carries `projectSlug`; branch-rename handler reuses
  it instead of re-reading git in hot paths.
- Status projection derives slug once per call and uses route hostname
  when available; only falls back to building when no route exists.
- Spawn cleanup removes routes by `{ workspaceId, scriptName }` so
  cleanup after a branch rename doesn't leave a stale entry behind.

App and shared message tests updated to the new fixture shape; service
URLs continue to be opaque server-provided strings.

Landing-page service URL examples updated; allowlist docs unchanged.

packages/server/src/shared/messages.workspaces.test.ts

@@ -138,9 +138,9 @@ describe("workspace message schemas", () => {
           scripts: [
             {
               scriptName: "web",
-              hostname: "web.localhost",
+              hostname: "web.paseo.localhost",
               port: 3000,
-              proxyUrl: "http://web.localhost:6767",
+              proxyUrl: "http://web.paseo.localhost:6767",
               lifecycle: "running",
               health: "healthy",
             },
@@ -157,9 +157,9 @@ describe("workspace message schemas", () => {
       {
         scriptName: "web",
         type: "service",
-        hostname: "web.localhost",
+        hostname: "web.paseo.localhost",
         port: 3000,
-        proxyUrl: "http://web.localhost:6767",
+        proxyUrl: "http://web.paseo.localhost:6767",
         lifecycle: "running",
         health: "healthy",
         exitCode: null,
@@ -204,7 +204,7 @@ describe("workspace message schemas", () => {
         scripts: [
           {
             scriptName: "web",
-            hostname: "web.localhost",
+            hostname: "web.paseo.localhost",
             port: null,
             proxyUrl: null,
             lifecycle: "stopped",