fix(desktop): avoid local profile REST backend spawns

[embwl0x]

Summary

Fixes #61023.

Hermes One can start an extra isolated dashboard backend for a local non-primary profile during startup because the Electron hermes:api proxy treated every request.profile as a backend-process routing key. Profile-scoped startup/config/session reads then call ensureBackend(profile), which launches a pooled --profile <name> dashboard/serve backend even though the primary machine dashboard can serve local profiles through ?profile=.

This keeps ordinary local-profile REST on the primary backend and appends ?profile=<name> to the proxied path instead. Per-profile remote overrides and app-global remote mode still route through profile descriptors so remote hosts keep working. Live chat sockets still use the existing lazy secondary backend path; this only changes REST routing.

Refresh note

Rebuilt onto current main after the desktop app moved from CommonJS Electron files to TypeScript/ESM. The routing helper and IPC coverage now live in the current .ts files.

Duplicate / overlap check

• Exact PR search: 61023 in:title,body returned no open PRs.
• Preflight script was warning-only for broad dashboard/profile/backend overlap.
• Manually checked the closest overlaps:
  • fix: isolate dashboard profile backends from cross-profile session reads #48652 isolates profile backends after they exist; this PR avoids spawning a local isolated backend for REST in the first place.
  • fix(desktop): route profile roster through active profile #57810 routes remote/fleet profile roster reads; this PR handles the local-profile REST route in the general IPC proxy.
  • fix(cli): reap dashboard/serve backends launched with pre-subcommand flags on update #60606 fixes stale dashboard process cleanup after update, not startup routing.

Verification

• cd apps/desktop && node --import tsx --test electron/connection-config.test.ts electron/profile-delete-respawn.test.ts — 57 passed
• npm --prefix apps/desktop run typecheck
• git diff --check origin/main..HEAD
• gitleaks git --log-opts='origin/main..HEAD' --redact . — no leaks found