fix(s3): preserve exact policy document in embedded IAM put/get-user-policy (#9025)

* fix(s3): preserve exact policy document in embedded IAM PutUserPolicy/GetUserPolicy (#9008)

The embedded IAM implementation (used when IAM requests go through the
S3 gateway) discarded the original policy document on PutUserPolicy,
storing only the lossy ident.Actions representation. GetUserPolicy then
reconstructed the document from these coarse-grained actions, producing
wildcard-expanded actions (s3:GetObject → s3:Get*), duplicates, and
collapsed resources (array → single string).

PR #9009 fixed this in the standalone IAM server (weed/iamapi/) but the
embedded IAM (weed/s3api/) — which is the code path most users hit —
had the same bugs.

Changes:

- Add InlinePolicyStore optional interface to credential store, with
  implementations for FilerEtcStore (uses existing PoliciesCollection),
  MemoryStore, and PropagatingCredentialStore.

- Embedded IAM PutUserPolicy now persists the original policy document
  via CredentialManager.PutUserInlinePolicy for lossless round-trips.

- Embedded IAM GetUserPolicy first tries the stored inline policy; only
  falls back to lossy reconstruction from ident.Actions when no stored
  document exists (e.g. policies created before this fix).

- Fix the fallback reconstruction: add action deduplication and preserve
  resource paths verbatim (no more spurious /* appending).

- Update DeleteUserPolicy/ListUserPolicies to use stored inline policies.

* fix(s3): address PR review feedback for embedded IAM inline policies

- Validate PolicyName is non-empty in PutUserPolicy and DeleteUserPolicy
- Add recomputeActions() to aggregate ident.Actions from ALL stored
  inline policies on put/delete, fixing the issue where a second
  PutUserPolicy would overwrite the first policy's enforcement
- Log errors from GetUserInlinePolicy in the GetUserPolicy fallback
  instead of silently ignoring them
- Add initialization guards to MemoryStore GetUserInlinePolicy and
  ListUserInlinePolicies for consistency with other read methods

* fix(s3): make inline policy persistence fatal and propagate recompute errors

Address second round of review feedback:

- recomputeActions() now returns ([]string, error) so callers can
  distinguish store failures from "no stored policies" and abort the
  mutation on transient errors instead of silently falling back.

- PutUserInlinePolicy and DeleteUserInlinePolicy failures are now fatal:
  the API call returns ServiceFailure instead of logging and continuing,
  keeping ident.Actions and stored policy state in sync.

* chore: gofmt weed/s3api/iceberg/handlers_oauth.go

Pre-existing formatting issue from #9017; fixes S3 Tables Format Check CI.

weed/s3api/s3api_embedded_iam_test.go

@@ -1259,6 +1259,82 @@ func TestEmbeddedIamCreateAccessKeyForExistingUser(t *testing.T) {
 	assert.Len(t, api.mockConfig.Identities[0].Credentials, 1)
 }
 
+// TestEmbeddedIamPutGetUserPolicyRoundTrip is a regression test for
+// https://github.com/seaweedfs/seaweedfs/issues/9008: put-user-policy followed
+// by get-user-policy must return the same policy document, with Action and Resource
+// lists intact (no wildcard expansion, no duplication, no collapsing).
+func TestEmbeddedIamPutGetUserPolicyRoundTrip(t *testing.T) {
+	api := NewEmbeddedIamApiForTest()
+	s3cfg := &iam_pb.S3ApiConfiguration{
+		Identities: []*iam_pb.Identity{{Name: "steward"}},
+	}
+	api.mockConfig = s3cfg
+
+	policyJSON := `{
+    "Version": "2012-10-17",
+    "Statement": [{
+      "Effect": "Allow",
+      "Action": ["s3:GetObject", "s3:PutObject", "s3:ListBucket"],
+      "Resource": ["arn:aws:s3:::b-le*", "arn:aws:s3:::b-le*/*"]
+    }]
+  }`
+
+	// PutUserPolicy
+	_, iamErr := api.PutUserPolicy(s3cfg, url.Values{
+		"UserName":       []string{"steward"},
+		"PolicyName":     []string{"steward_policy"},
+		"PolicyDocument": []string{policyJSON},
+	})
+	assert.Nil(t, iamErr)
+
+	// GetUserPolicy should return the exact document
+	resp, iamErr := api.GetUserPolicy(s3cfg, url.Values{
+		"UserName":   []string{"steward"},
+		"PolicyName": []string{"steward_policy"},
+	})
+	assert.Nil(t, iamErr)
+
+	var got policy_engine.PolicyDocument
+	assert.NoError(t, json.Unmarshal([]byte(resp.GetUserPolicyResult.PolicyDocument), &got))
+
+	assert.Equal(t, "2012-10-17", got.Version)
+	require.Equal(t, 1, len(got.Statement))
+	stmt := got.Statement[0]
+	assert.Equal(t, policy_engine.PolicyEffectAllow, stmt.Effect)
+	assert.ElementsMatch(t, []string{"s3:GetObject", "s3:PutObject", "s3:ListBucket"}, stmt.Action.Strings())
+	assert.ElementsMatch(t, []string{"arn:aws:s3:::b-le*", "arn:aws:s3:::b-le*/*"}, stmt.Resource.Strings())
+}
+
+// TestEmbeddedIamGetUserPolicyFallback tests the lossy fallback reconstruction
+// when no stored inline policy is available (pre-existing ident.Actions only).
+func TestEmbeddedIamGetUserPolicyFallback(t *testing.T) {
+	api := NewEmbeddedIamApiForTest()
+	s3cfg := &iam_pb.S3ApiConfiguration{
+		Identities: []*iam_pb.Identity{{
+			Name:    "steward",
+			Actions: []string{"Read:b-le*", "Write:b-le*", "List:b-le*", "Read:b-le*/*", "Write:b-le*/*", "List:b-le*/*"},
+		}},
+	}
+	api.mockConfig = s3cfg
+
+	// No stored inline policy — GetUserPolicy must reconstruct from ident.Actions
+	resp, iamErr := api.GetUserPolicy(s3cfg, url.Values{
+		"UserName":   []string{"steward"},
+		"PolicyName": []string{"steward_policy"},
+	})
+	assert.Nil(t, iamErr)
+
+	var got policy_engine.PolicyDocument
+	assert.NoError(t, json.Unmarshal([]byte(resp.GetUserPolicyResult.PolicyDocument), &got))
+
+	// Fallback is lossy but must not duplicate actions
+	require.Equal(t, 1, len(got.Statement), "fallback should merge equal-action statements")
+	stmt := got.Statement[0]
+	assert.ElementsMatch(t, []string{"s3:Get*", "s3:Put*", "s3:List*"}, stmt.Action.Strings())
+	// Bucket-level and object-level resources stay distinct
+	assert.ElementsMatch(t, []string{"arn:aws:s3:::b-le*", "arn:aws:s3:::b-le*/*"}, stmt.Resource.Strings())
+}
+
 // TestEmbeddedIamGetUserPolicyUserNotFound tests GetUserPolicy with non-existent user
 func TestEmbeddedIamGetUserPolicyUserNotFound(t *testing.T) {
 	api := NewEmbeddedIamApiForTest()