fix(task-create): handle WorkflowAlreadyStartedError gracefully

[alvinkam2001]

Greptile Summary

This PR makes duplicate Temporal task starts return the existing workflow and adds default OpenTelemetry context propagation across Temporal clients and workers.

• Adds workflow-ID conflict-policy plumbing and uses USE_EXISTING for task submission.
• Installs a configurable Temporal tracing interceptor on client and worker boundaries.
• Adds unit coverage for conflict-policy forwarding and tracing-interceptor configuration.

Confidence Score: 4/5

The PR should not merge until duplicate task IDs with changed inputs are rejected or reconciled instead of being reported as successful while silently retaining the old workflow inputs.

USE_EXISTING handles exact retries, but it also converts conflicting submissions with updated agent, params, or timeout values into apparent successes even though Temporal does not apply those new workflow-start arguments.

Files Needing Attention: src/agentex/lib/core/temporal/services/temporal_task_service.py

Important Files Changed

Filename	Overview
src/agentex/lib/core/temporal/services/temporal_task_service.py	Makes task submission idempotent through USE_EXISTING, but silently discards changed inputs when a duplicate ID refers to an active workflow.
src/agentex/lib/core/clients/temporal/temporal_client.py	Adds conflict-policy plumbing from the wrapper to Temporal's workflow-start API.
src/agentex/lib/core/tracing/temporal.py	Adds opt-out, failure-tolerant construction of Temporal's OpenTelemetry interceptor.
src/agentex/lib/core/clients/temporal/utils.py	Enables trace-context injection on SDK Temporal clients.
src/agentex/lib/core/temporal/workers/worker.py	Enables tracing on the worker's client and places the tracing worker interceptor before business interceptors.
tests/lib/core/services/test_temporal_task_service.py	Covers conflict-policy forwarding but only tests exact-retry behavior, not duplicate IDs with differing payloads.
tests/lib/core/tracing/test_temporal_interceptor.py	Covers default enablement, supported opt-out values, and unavailable-contrib fallback.

Sequence Diagram

sequenceDiagram
    participant Caller
    participant ACP as TemporalACP
    participant Service as TemporalTaskService
    participant Temporal
    Caller->>ACP: task/create(task ID, params)
    ACP->>Service: submit_task(agent, task, params)
    Service->>Temporal: start_workflow(id, inputs, USE_EXISTING)
    alt No active workflow
        Temporal-->>Service: New workflow handle
    else Active workflow with same ID
        Temporal-->>Service: Existing workflow handle
        Note over Service,Temporal: New inputs are not delivered
    end
    Service-->>ACP: Task ID

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Prompt To Fix All With AI

### Issue 1
src/agentex/lib/core/temporal/services/temporal_task_service.py:59
**Conflicting task inputs are discarded**

When a second `task/create` request resolves to an active task ID but supplies changed agent, params, or timeout values, `USE_EXISTING` reports success without delivering the new `CreateTaskParams` to the workflow, causing the running task to retain its original inputs despite the task/create contract allowing supplied params to overwrite existing params.

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For each issue above, determine whether it is valid and should be fixed. If so, fix it directly.

_{Reviews (1): Last reviewed commit: "handle same workflow task/create gracefu..." | Re-trigger Greptile}

Greptile also left 1 inline comment on this PR.

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[greptile-apps]

Conflicting task inputs are discarded

When a second task/create request resolves to an active task ID but supplies changed agent, params, or timeout values, USE_EXISTING reports success without delivering the new CreateTaskParams to the workflow, causing the running task to retain its original inputs despite the task/create contract allowing supplied params to overwrite existing params.

Prompt To Fix With AI

This is a comment left during a code review.
Path: src/agentex/lib/core/temporal/services/temporal_task_service.py
Line: 59

Comment:
**Conflicting task inputs are discarded**

When a second `task/create` request resolves to an active task ID but supplies changed agent, params, or timeout values, `USE_EXISTING` reports success without delivering the new `CreateTaskParams` to the workflow, causing the running task to retain its original inputs despite the task/create contract allowing supplied params to overwrite existing params.

---

For each issue above, determine whether it is valid and should be fixed. If so, fix it directly.