feat(alerting): SSRF guard on outbound connection URL

Rejects webhook URLs that resolve to loopback, link-local, or RFC-1918
private ranges (IPv4 + IPv6 ULA fc00::/7). Enforced on both create and
update in OutboundConnectionServiceImpl before persistence; returns 400
Bad Request with "private or loopback" in the body.

Bypass via `cameleer.server.outbound-http.allow-private-targets=true`
for dev environments where webhooks legitimately point at local
services. Production default is `false`.

Test profile sets the flag to `true` in application-test.yml so the
existing ITs that post webhooks to WireMock on https://localhost:PORT
keep working. A dedicated OutboundConnectionSsrfIT overrides the flag
back to false (via @TestPropertySource + @DirtiesContext) to exercise
the reject path end-to-end through the admin controller.

Plan 01 scope; required before SaaS exposure (spec §17).

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

cameleer-server-app/src/test/resources/application-test.yml

@@ -17,3 +17,5 @@ cameleer:
       bootstraptokenprevious: old-bootstrap-token
       infrastructureendpoints: true
       jwtsecret: test-jwt-secret-for-integration-tests-only
+    outbound-http:
+      allow-private-targets: true