feat: [Cadence Schedules] Add schedule API request/response types (#7749)

**What changed?**
- Add request/response types for all Schedule CRUD and lifecycle APIs
(Create, Describe, Update, Delete, Pause, Unpause, List, Backfill) in
`common/types/schedule_service.go`
- Add `ScheduleListEntry` for paginated list responses
- Include nil-safe getters for every field on every type, consistent
  with existing patterns in `common/types/shared.go`
- Add `schedule_service_test.go` with nil-receiver and value getter
tests

**Why?**
To support the new Cadence Schedules feature (pause/resume, catch-up,
backfill), we need internal Go types to represent schedule entities
within the server codebase. These types mirror the IDL definitions. This
serves as the foundation for the scheduler workflow and API
implementation.

Builds on [#7745](#7745)
which introduced the core schedule types and enums.

**How did you test it?**
Added unit tests and ran go test ./.. on the added files 

**Potential risks**
N/A

**Release notes**
Added request/response types for cadence schedules

**Documentation Changes**
N/A

---

## Reviewer Validation

**PR Description Quality** (check these before reviewing code):

- [ ] **"What changed"** provides a clear 1-2 line summary
  - [ ] Project Issue is linked
- [ ] **"Why"** explains the full motivation with sufficient context
- [ ] **Testing is documented:**
- [ ] Unit test commands are included (with exact `go test` invocation)
- [ ] Integration test setup/commands included (if integration tests
were run)
  - [ ] Canary testing details included (if canary was mentioned)
- [ ] **Potential risks** section is thoughtfully filled out (or
legitimately N/A)
- [ ] **Release notes** included if this completes a user-facing feature
- [ ] **Documentation** needs are addressed (or noted if uncertain)

Signed-off-by: abhishek.jha <abhishek.jha@uber.com>

Author: abhishekj720

common/types/schedule.go

@@ -181,13 +181,13 @@ func (v *ScheduleSpec) GetJitter() (o time.Duration) {
 type StartWorkflowAction struct {
 	WorkflowType                        *WorkflowType     `json:"workflowType,omitempty"`
 	TaskList                            *TaskList         `json:"taskList,omitempty"`
-	Input                               []byte            `json:"-"`
+	Input                               []byte            `json:"-"` // Potential PII
 	WorkflowIDPrefix                    string            `json:"workflowIdPrefix,omitempty"`
 	ExecutionStartToCloseTimeoutSeconds *int32            `json:"executionStartToCloseTimeoutSeconds,omitempty"`
 	TaskStartToCloseTimeoutSeconds      *int32            `json:"taskStartToCloseTimeoutSeconds,omitempty"`
 	RetryPolicy                         *RetryPolicy      `json:"retryPolicy,omitempty"`
-	Memo                                *Memo             `json:"-"`
-	SearchAttributes                    *SearchAttributes `json:"-"`
+	Memo                                *Memo             `json:"-"` // Filtering PII
+	SearchAttributes                    *SearchAttributes `json:"-"` // Filtering PII
 }
 
 func (v *StartWorkflowAction) GetWorkflowType() *WorkflowType {
@@ -384,12 +384,12 @@ func (v *BackfillInfo) GetRunsTotal() (o int32) {
 
 // ScheduleInfo provides runtime information about the schedule.
 type ScheduleInfo struct {
-	LastRunTime      time.Time      `json:"lastRunTime,omitempty"`
-	NextRunTime      time.Time      `json:"nextRunTime,omitempty"`
-	TotalRuns        int64          `json:"totalRuns,omitempty"`
-	CreateTime       time.Time      `json:"createTime,omitempty"`
-	LastUpdateTime   time.Time      `json:"lastUpdateTime,omitempty"`
-	OngoingBackfills []BackfillInfo `json:"ongoingBackfills,omitempty"`
+	LastRunTime      time.Time       `json:"lastRunTime,omitempty"`
+	NextRunTime      time.Time       `json:"nextRunTime,omitempty"`
+	TotalRuns        int64           `json:"totalRuns,omitempty"`
+	CreateTime       time.Time       `json:"createTime,omitempty"`
+	LastUpdateTime   time.Time       `json:"lastUpdateTime,omitempty"`
+	OngoingBackfills []*BackfillInfo `json:"ongoingBackfills,omitempty"`
 }
 
 func (v *ScheduleInfo) GetLastRunTime() (o time.Time) {
@@ -427,7 +427,7 @@ func (v *ScheduleInfo) GetLastUpdateTime() (o time.Time) {
 	return
 }
 
-func (v *ScheduleInfo) GetOngoingBackfills() (o []BackfillInfo) {
+func (v *ScheduleInfo) GetOngoingBackfills() (o []*BackfillInfo) {
 	if v != nil {
 		return v.OngoingBackfills
 	}