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.

ingest/internal/agentregistry/agentregistry.go

@@ -34,11 +34,12 @@ const defaultTenantID = "default"
 // across a module boundary rather than couple two independently
 // deployable services' builds together. Keep the two in sync by hand.
 type overrideFields struct {
-	BatchMaxSize         *uint64 `json:"batch_max_size,omitempty"`
-	BatchFlushIntervalMS *uint64 `json:"batch_flush_interval_ms,omitempty"`
-	HeartbeatEnabled     *bool   `json:"heartbeat_enabled,omitempty"`
-	HeartbeatIntervalMS  *uint64 `json:"heartbeat_interval_ms,omitempty"`
-	JournaldUnit         *string `json:"journald_unit,omitempty"`
+	BatchMaxSize         *uint64  `json:"batch_max_size,omitempty"`
+	BatchFlushIntervalMS *uint64  `json:"batch_flush_interval_ms,omitempty"`
+	HeartbeatEnabled     *bool    `json:"heartbeat_enabled,omitempty"`
+	HeartbeatIntervalMS  *uint64  `json:"heartbeat_interval_ms,omitempty"`
+	JournaldUnit         *string  `json:"journald_unit,omitempty"`
+	ExtraFilePaths       []string `json:"extra_file_paths,omitempty"`
 }
 
 type Registry struct {
@@ -146,6 +147,7 @@ func (r *Registry) CheckIn(ctx context.Context, tenantID string, info grpcserver
 		HeartbeatEnabled:     fields.HeartbeatEnabled,
 		HeartbeatIntervalMS:  fields.HeartbeatIntervalMS,
 		JournaldUnit:         fields.JournaldUnit,
+		ExtraFilePaths:       fields.ExtraFilePaths,
 		Version:              *desiredVersion,
 	}
 	return result, nil