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.

api/internal/querylang/planner/planner.go

@@ -259,6 +259,24 @@ func defaultAggAlias(a ast.AggCall) string {
 // SQL parser -- same tradeoffs as the Phase 0/1 version this replaces.
 var disallowedKeyword = regexp.MustCompile(`(?i)\b(insert|update|delete|alter|drop|truncate|create|grant|revoke|attach|detach|rename|kill|optimize|system|set|exchange|watch)\b`)
 
+// disallowedTableFunction blocks ClickHouse's built-in table functions
+// that reach outside ClickHouse itself -- a keyword blocklist for
+// mutating statements (above) doesn't touch these at all, since
+// `SELECT * FROM url(...)` is a perfectly ordinary read-only SELECT as
+// far as validateSelectOnly's other checks are concerned. Every
+// function here lets a SELECT-only, RoleViewer-gated query make
+// ClickHouse itself issue an outbound request or read a local file on
+// the caller's behalf -- cloud-metadata SSRF via url(), a proxy into
+// other internal ClickHouse/MySQL/Postgres instances via
+// remote()/remoteSecure()/mysql()/postgresql(), and local/object-storage
+// file reads via file()/hdfs()/s3()/azureBlobStorage()/deltaLake()/
+// iceberg()/hudi(). Same word-boundary-regex tradeoff as
+// disallowedKeyword above: this is a blocklist, not a real SQL parser,
+// so it can't be the only control -- see the ClickHouse-grant-level
+// hardening this should be paired with (table-function usage revoked
+// for the role api's raw-SQL path connects as).
+var disallowedTableFunction = regexp.MustCompile(`(?i)\b(url|remote|remoteSecure|mysql|postgresql|s3|s3Cluster|hdfs|hdfsCluster|file|odbc|jdbc|executable|cluster|clusterAllReplicas|azureBlobStorage|deltaLake|iceberg|hudi|redis|mongodb)\s*\(`)
+
 func validateSelectOnly(sql string) error {
 	trimmed := strings.TrimSpace(sql)
 	if trimmed == "" {
@@ -281,6 +299,9 @@ func validateSelectOnly(sql string) error {
 	if disallowedKeyword.MatchString(trimmed) {
 		return fmt.Errorf("query contains a disallowed keyword")
 	}
+	if disallowedTableFunction.MatchString(trimmed) {
+		return fmt.Errorf("query contains a disallowed table function")
+	}
 
 	return nil
 }