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.

cli/cmd/sentryctl/main.go

@@ -40,6 +40,8 @@ func run(args []string, stdout, stderr io.Writer) int {
 		return cmdAlerts(args[1:], stdout, stderr)
 	case "agents":
 		return cmdAgents(args[1:], stdout, stderr)
+	case "users":
+		return cmdUsers(args[1:], os.Stdin, stdout, stderr)
 	case "-h", "--help", "help":
 		usage(stdout)
 		return 0
@@ -67,6 +69,11 @@ Usage:
                               [--heartbeat-enabled true|false] [--heartbeat-interval-ms N]
                               [--journald-unit UNIT] [--api <url>]
   sentryctl agents restart <host> [--yes] [--api <url>]
+  sentryctl users login <username> [--password <pw>] [--api <url>]
+  sentryctl users list [--api <url>]
+  sentryctl users create <username> [--password <pw>] [--role viewer|editor|admin|owner] [--api <url>]
+  sentryctl users delete <id> [--api <url>]
+  sentryctl users reset-password <id> [--password <pw>] [--api <url>]
 
 Commands:
   ping        Checks that the api service is reachable via GET /healthz.
@@ -95,6 +102,17 @@ Commands:
               as the web UI's edit form. "restart" briefly interrupts
               log collection on that host and prompts for confirmation
               unless --yes is given.
+  users       Local username/password login and user management (see
+              api/localauth -- only meaningful on a deployment with
+              LOCAL_AUTH_ENABLED set; a 404 on any of these means it
+              isn't). "login" is the only command that works with no
+              $SENTRYCTL_TOKEN set yet -- it prints just the raw token
+              to stdout: `+"`export SENTRYCTL_TOKEN=$(sentryctl users login admin)`"+`.
+              --password (on any users subcommand) is read from stdin
+              if omitted -- same shell-history/ps caveat as typing a
+              credential in any flag, prefer piping it in.
+              "create"/"list"/"delete"/"reset-password" require an
+              owner-role token (see RegisterRoutes in api/localauth).
 
 --api defaults to $SENTRYCTL_API_URL, or `+defaultAPIURL+` if unset.
 --alerting-api defaults to $SENTRYCTL_ALERTING_API_URL, or `+defaultAlertingURL+` if unset.