uptime kuma: remove every live reference, repoint the probes to Gatus

Nothing in the repo pushes to, authenticates against, or is gated by Uptime
Kuma any more.

── The sixth instance of the banner bug ────────────────────────────────────
memos had `Restart memos` guarded by `uptime_kuma_enabled`, because the
deprecation banner was placed immediately above it and swept it in. It is a
HANDLER, so every memos config change since 2026-09-11 applied to disk and
silently never restarted the service. Ungated.

That is the same failure found in forgejo-runner's self-assert, phoenixd's timer
enable, mempool's three timer enables, fulcrum's restart handler and bitcoind's
restart handler. Every guard was read and asked "monitoring or deployment?"
before being deleted, which is the only reason this was caught.

── What was removed ────────────────────────────────────────────────────────
  30 uptime_kuma_enabled guards across 7 unconverted service playbooks, and
     the 29 Kuma monitor-creation tasks they gated (embedded Python that drove
     the Kuma API, temp credential files, cleanup)
  7  dead uptime_kuma_api_url definitions
  7  stale DEPRECATED banners
     uptime_kuma_enabled and subdomains.uptime_kuma from group_vars/all
     healthcheck_push_urls from the vault - 30 push tokens
     services/ntfy/setup_ntfy_uptime_kuma_notification.yml -> archive/

The explanatory comments in the six converted roles are KEPT on purpose. They
record why a handler is ungated, and deleting the explanation invites someone
to helpfully re-add the guard.

── The probes moved rather than died ───────────────────────────────────────
Eight per-service health checks were still pushing to Kuma. They are not
superseded by infra/401: that answers "is the unit running", these answer "does
the service actually respond" - an RPC call to bitcoind, a TCP connect to
Fulcrum's Electrum port, an HTTP fetch from Mempool's backend. A process can be
perfectly `active` and useless.

So they were repointed, not deleted. Gatus external endpoints take a POST with
a bearer token and success=true|false where Kuma took a GET with ?status=up, so
report() now maps up/down to true/false internally and no call site changed.
Registered by infra/403 as the `probe` group, one token per host.

Two bugs fixed while in there:
  * forgejo-runner's check only ever reported SUCCESS - it exited before pushing
    when the runner was down, so a failure was invisible until the heartbeat
    window expired. Reporting the failure is the entire point of a check.
  * All six healthcheck .service units were mode 0644 and now carry a bearer
    token. They are 0600.

Verified: 91 endpoints, 91 UP, 0 DOWN. Every probe triggered by hand and
confirmed arriving. Zero Kuma URLs left in the vault, zero live references in
any playbook or role.

Still standing, deliberately: the Kuma container on watchtower, its Caddy vhost,
and the uptime.contrapeso.xyz DNS record. Turning the service off is a separate
decision from removing the code that talked to it.

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

ansible/roles/fulcrum/templates/healthcheck.service.j2

@@ -7,6 +7,7 @@ Type=oneshot
 User=root
 ExecStart=/usr/local/bin/fulcrum-healthcheck-push.sh
 Environment=HEALTHCHECK_PUSH_URL={{ healthcheck_push_url }}
+Environment=HEALTHCHECK_PUSH_TOKEN={{ healthcheck_push_token }}
 StandardOutput=journal
 StandardError=journal
 

ansible/roles/fulcrum/templates/healthcheck.sh.j2

@@ -10,6 +10,7 @@
 FULCRUM_HOST="{{ fulcrum_tcp_bind }}"
 FULCRUM_PORT={{ fulcrum_tcp_port }}
 PUSH_URL="${HEALTHCHECK_PUSH_URL:-}"
+PUSH_TOKEN="${HEALTHCHECK_PUSH_TOKEN:-}"
 
 check_fulcrum() {
     timeout 5 bash -c "echo > /dev/tcp/${FULCRUM_HOST}/${FULCRUM_PORT}" 2>/dev/null
@@ -20,8 +21,14 @@ report() {
     # No push URL is normal, not an error: the exit code below is still a
     # complete answer for anything reading unit state.
     [ -n "$PUSH_URL" ] || return 0
-    curl -s --max-time 10 --retry 2 -o /dev/null \
-        "${PUSH_URL}?status=${status}&msg=${msg// /%20}&ping=" || true
+    # Gatus external endpoint: a POST with a bearer token, NOT Uptime Kuma's
+    # GET with ?status=up. The callers still pass up/down, so the mapping is
+    # done here rather than at every call site.
+    local _ok=false
+    [ "${status}" = "up" ] && _ok=true
+    curl -s --max-time 15 --retry 2 -o /dev/null -X POST \
+        -H "Authorization: Bearer ${PUSH_TOKEN}" \
+        "${PUSH_URL}?success=${_ok}&error=${msg// /%20}" || true
 }
 
 if check_fulcrum; then