Add local login, agent extra log paths, IPv4/IPv6 metrics; remediate security audit findings

This is a large squashed commit covering two batches of prior uncommitted
work plus a full security-audit remediation pass, kept together because
go.mod/go.sum and several shared files (main.go, handler.go) were touched
by both and splitting risked non-building intermediate commits.

Features (built earlier, previously uncommitted):
- Local username/password login for single-tenant deployments with no
  SSO configured (api/localauth, alerting/internal/sessioncheck,
  sentryctl users, web/src/routes/login, metadata migrations 0040/0041).
- Remotely-editable additional log file paths for agents, on top of
  their existing primary source (api/agents, agent/sentry-agent
  extra-file-path diffing, web agent config UI).
- IPv4/IPv6 addresses reported alongside other host system metrics.

Security audit remediation (this pass, all live-verified in production):
- Critical: block ClickHouse SSRF table functions (url/remote/file/s3/...)
  in the raw-SQL query escape hatch.
- High: deny sensitive paths and require Admin to add agent
  extra_file_paths (Editor could previously point an agent at /etc/shadow
  or an SSH key); alerting webhook targets now validate against
  internal/metadata/loopback addresses, both at creation and send time;
  alerting's session middleware now enforces an Editor+ floor on
  mutating requests instead of "any authenticated session"; bumped
  goxmldsig to close a SAML signature-verification bypass (GO-2026-4753).
- Medium: per-IP login rate limiting; security response headers
  (HSTS/CSP/nosniff/X-Frame-Options/Referrer-Policy/Permissions-Policy)
  on web/nginx.conf; a DevCredentialWarnings check in every Go service's
  config loader, logging loudly at startup if a deployment is still on
  docker-compose.yml's literal dev-only credentials; dependency bumps
  (golang.org/x/text, grpc, x/net, quick-xml, h2) across every affected
  Go module and both Rust crates, including a previously-uncovered x/net
  vulnerability in deploy/operator; a new security-scan.yml CI workflow
  running cargo-deny/govulncheck/npm-audit, mirroring the existing
  license-compliance.yml matrix shape.
- Low: removed sentryctl's plaintext --password flag (shell
  history/`ps` exposure) in favor of stdin and a --password-stdin flag
  for reset-password's optional specific-password path; a dummy bcrypt
  comparison closes a login response-time username-enumeration
  side-channel.

enterprise/go.mod

@@ -36,6 +36,7 @@ require (
 	github.com/jackc/pgx/v5 v5.10.0
 	github.com/sentry/sentry/proto v0.0.0-00010101000000-000000000000
 	golang.org/x/oauth2 v0.36.0
+	golang.org/x/sync v0.22.0
 	google.golang.org/grpc v1.83.0
 	k8s.io/api v0.31.0
 	k8s.io/apimachinery v0.31.0
@@ -45,7 +46,7 @@ require (
 require (
 	github.com/ClickHouse/ch-go v0.74.0 // indirect
 	github.com/andybalholm/brotli v1.2.2 // indirect
-	github.com/beevik/etree v1.5.0 // indirect
+	github.com/beevik/etree v1.6.0 // indirect
 	github.com/cespare/xxhash/v2 v2.3.0 // indirect
 	github.com/davecgh/go-spew v1.1.2-0.20180830191138-d8f796af33cc // indirect
 	github.com/emicklei/go-restful/v3 v3.11.0 // indirect
@@ -66,7 +67,7 @@ require (
 	github.com/jackc/pgpassfile v1.0.0 // indirect
 	github.com/jackc/pgservicefile v0.0.0-20240606120523-5a60cdf6a761 // indirect
 	github.com/jackc/puddle/v2 v2.2.2 // indirect
-	github.com/jonboulle/clockwork v0.2.2 // indirect
+	github.com/jonboulle/clockwork v0.5.0 // indirect
 	github.com/josharian/intern v1.0.0 // indirect
 	github.com/json-iterator/go v1.1.12 // indirect
 	github.com/klauspost/compress v1.19.1 // indirect
@@ -78,7 +79,7 @@ require (
 	github.com/paulmach/orb v0.13.0 // indirect
 	github.com/pierrec/lz4/v4 v4.1.27 // indirect
 	github.com/pkg/errors v0.9.1 // indirect
-	github.com/russellhaering/goxmldsig v1.4.0 // indirect
+	github.com/russellhaering/goxmldsig v1.6.0 // indirect
 	github.com/segmentio/asm v1.2.1 // indirect
 	github.com/segmentio/kafka-go v0.4.51 // indirect
 	github.com/shopspring/decimal v1.4.0 // indirect
@@ -86,12 +87,11 @@ require (
 	github.com/x448/float16 v0.8.4 // indirect
 	go.opentelemetry.io/otel v1.44.0 // indirect
 	go.opentelemetry.io/otel/trace v1.44.0 // indirect
-	golang.org/x/crypto v0.54.0 // indirect
+	golang.org/x/crypto v0.55.0 // indirect
 	golang.org/x/net v0.57.0 // indirect
-	golang.org/x/sync v0.22.0 // indirect
 	golang.org/x/sys v0.47.0 // indirect
 	golang.org/x/term v0.45.0 // indirect
-	golang.org/x/text v0.40.0 // indirect
+	golang.org/x/text v0.41.0 // indirect
 	golang.org/x/time v0.3.0 // indirect
 	google.golang.org/genproto/googleapis/rpc v0.0.0-20260526163538-3dc84a4a5aaa // indirect
 	google.golang.org/protobuf v1.36.12 // indirect