fix(windows/web): start the console once its inputs exist, and verify it started

A fresh install left PunktfunkWeb registered but not running: `web setup` waited
only for the mgmt token before firing `schtasks /run`, while `web-run.cmd` also
requires the host identity cert — and the host writes the token during argument
parsing but `cert.pem` only after the pure-Rust RSA-2048 keygen inside `serve`.
The launcher lost that race, exited 1, and since the task carried no trigger but
boot (Task Scheduler does not reliably restart on a non-zero exit code) the
console stayed down until the next reboot, with the installer still reporting
"web console set up + started".

- `web setup` gates on cert.pem (written last) as well as the token, 90 s budget.
- After `schtasks /run`, poll for the :47992 listener and retry before giving up;
  warn honestly instead of claiming a start that did not happen.
- `web-run.cmd` (installed + dev) waits in-process for the token + cert (~5 min)
  rather than exiting 1 and hoping restart-on-failure retries.
- Register the task with a logon trigger alongside boot, falling back to the
  boot-only XML if a Task Scheduler build rejects it.
- Linux had the same defect: punktfunk-web.service's Restart=on-failure gave up
  permanently after systemd's default 5-starts-in-10 s limit. StartLimitIntervalSec=0.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

docs-site/content/docs/windows-host.md

@@ -66,7 +66,7 @@ the Windows specifics follow.
 
 The installer also sets up the **web management console** (status, paired devices, the PIN pairing
 flow): it bundles the console plus its own runtime and runs it as the **`PunktfunkWeb`** task on
-**`https://<this-PC>:47992`**, starting at boot.
+**`https://<this-PC>:47992`**, starting at boot and at sign-in.
 
 #### Console login password