S3: Implement IAM defaults and STS signing key fallback (#8348)

* S3: Implement IAM defaults and STS signing key fallback logic

* S3: Refactor startup order to init SSE-S3 key manager before IAM

* S3: Derive STS signing key from KEK using HKDF for security isolation

* S3: Document STS signing key fallback in security.toml

* fix(s3api): refine anonymous access logic and secure-by-default behavior

- Initialize anonymous identity by default in `NewIdentityAccessManagement` to prevent nil pointer exceptions.
- Ensure `ReplaceS3ApiConfiguration` preserves the anonymous identity if not present in the new configuration.
- Update `NewIdentityAccessManagement` signature to accept `filerClient`.
- In legacy mode (no policy engine), anonymous defaults to Deny (no actions), preserving secure-by-default behavior.
- Use specific `LookupAnonymous` method instead of generic map lookup.
- Update tests to accommodate signature changes and verify improved anonymous handling.

* feat(s3api): make IAM configuration optional

- Start S3 API server without a configuration file if `EnableIam` option is set.
- Default to `Allow` effect for policy engine when no configuration is provided (Zero-Config mode).
- Handle empty configuration path gracefully in `loadIAMManagerFromConfig`.
- Add integration test `iam_optional_test.go` to verify empty config behavior.

* fix(iamapi): fix signature mismatch in NewIdentityAccessManagementWithStore

* fix(iamapi): properly initialize FilerClient instead of passing nil

* fix(iamapi): properly initialize filer client for IAM management

- Instead of passing `nil`, construct a `wdclient.FilerClient` using the provided `Filers` addresses.
- Ensure `NewIdentityAccessManagementWithStore` receives a valid `filerClient` to avoid potential nil pointer dereferences or limited functionality.

* clean: remove dead code in s3api_server.go

* refactor(s3api): improve IAM initialization, safety and anonymous access security

* fix(s3api): ensure IAM config loads from filer after client init

* fix(s3): resolve test failures in integration, CORS, and tagging tests

- Fix CORS tests by providing explicit anonymous permissions config
- Fix S3 integration tests by setting admin credentials in init
- Align tagging test credentials in CI with IAM defaults
- Added goroutine to retry IAM config load in iamapi server

* fix(s3): allow anonymous access to health targets and S3 Tables when identities are present

* fix(ci): use /healthz for Caddy health check in awscli tests

* iam, s3api: expose DefaultAllow from IAM and Policy Engine

This allows checking the global "Open by Default" configuration from
other components like S3 Tables.

* s3api/s3tables: support DefaultAllow in permission logic and handler

Updated CheckPermissionWithContext to respect the DefaultAllow flag
in PolicyContext. This enables "Open by Default" behavior for
unauthenticated access in zero-config environments. Added a targeted
unit test to verify the logic.

* s3api/s3tables: propagate DefaultAllow through handlers

Propagated the DefaultAllow flag to individual handlers for
namespaces, buckets, tables, policies, and tagging. This ensures
consistent "Open by Default" behavior across all S3 Tables API
endpoints.

* s3api: wire up DefaultAllow for S3 Tables API initialization

Updated registerS3TablesRoutes to query the global IAM configuration
and set the DefaultAllow flag on the S3 Tables API server. This
completes the end-to-end propagation required for anonymous access in
zero-config environments. Added a SetDefaultAllow method to
S3TablesApiServer to facilitate this.

* s3api: fix tests by adding DefaultAllow to mock IAM integrations

The IAMIntegration interface was updated to include DefaultAllow(),
breaking several mock implementations in tests. This commit fixes
the build errors by adding the missing method to the mocks.

* env

* ensure ports

* env

* env

* fix default allow

* add one more test using non-anonymous user

* debug

* add more debug

* less logs

weed/command/mini.go

@@ -355,6 +355,9 @@ func isFlagPassed(name string) bool {
 
 // isPortOpenOnIP checks if a port is available for binding on a specific IP address
 func isPortOpenOnIP(ip string, port int) bool {
+	if port <= 0 || port > 65535 {
+		return false
+	}
 	listener, err := net.Listen("tcp", fmt.Sprintf("%s:%d", ip, port))
 	if err != nil {
 		return false
@@ -366,6 +369,9 @@ func isPortOpenOnIP(ip string, port int) bool {
 // isPortAvailable checks if a port is available on any interface
 // This is more comprehensive than checking a single IP
 func isPortAvailable(port int) bool {
+	if port <= 0 || port > 65535 {
+		return false
+	}
 	// Try to listen on all interfaces (0.0.0.0)
 	listener, err := net.Listen("tcp", fmt.Sprintf(":%d", port))
 	if err != nil {
@@ -381,6 +387,10 @@ func isPortAvailable(port int) bool {
 func findAvailablePortOnIP(ip string, startPort int, maxAttempts int, reservedPorts map[int]bool) int {
 	for i := 0; i < maxAttempts; i++ {
 		port := startPort + i
+		if port > 65535 {
+			// Wrap around to a lower range if we exceed 65535
+			port = 10000 + (port % 65535)
+		}
 		// Skip ports reserved for gRPC calculation
 		if reservedPorts[port] {
 			continue
@@ -398,15 +408,15 @@ func findAvailablePortOnIP(ip string, startPort int, maxAttempts int, reservedPo
 // If the port is not available, it finds the next available port and updates the pointer
 // The reservedPorts map contains ports that should not be allocated (for gRPC collision avoidance)
 func ensurePortAvailableOnIP(portPtr *int, serviceName string, ip string, reservedPorts map[int]bool, flagName string) error {
-	if portPtr == nil {
+	// Check if this port was explicitly specified by the user (from CLI, before config file was applied)
+	isExplicitPort := explicitPortFlags[flagName]
+
+	if *portPtr == 0 {
 		return nil
 	}
 
 	original := *portPtr
 
-	// Check if this port was explicitly specified by the user (from CLI, before config file was applied)
-	isExplicitPort := explicitPortFlags[flagName]
-
 	// Skip if this port is reserved for gRPC calculation
 	if reservedPorts[original] {
 		if isExplicitPort {