fix(mcp): retry connect calls on transient grpc errs

[sicoyle]

Description

This PR wraps the mcp connect calls (sync and async) with a bounded retry that absorbs CANCELLED or UNAVAILABLE grpc errs within the timeout budget specified. Any other err propagates.

Issue reference

We strive to have all PR being opened based on an issue, where the problem or feature have been discussed prior to implementation.

Please reference the issue this PR will close: #[issue number]

Checklist

Please make sure you've completed the relevant tasks for this PR, out of the following list:

• Code compiles correctly
• Created/updated tests
• Extended the documentation

[Copilot]

Pull request overview

This PR adds bounded retry behavior to MCP client connect() calls (sync + async) so that transient gRPC errors during workflow scheduling (CANCELLED, UNAVAILABLE) are retried within the caller-provided timeout budget, and updates the MCP client tests to cover these retry paths.

Changes:

• Add transient gRPC error classification and bounded retry loop around schedule_new_workflow() in sync DaprMCPClient.connect().
• Add the equivalent retry logic to async AioDaprMCPClient.connect().
• Add new unit tests validating retry success, non-transient propagation, and deadline exhaustion.

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 4 comments.

File	Description
ext/dapr-ext-workflow/dapr/ext/workflow/mcp.py	Implements transient-error classification + retry loop for sync MCP connect() scheduling, and adjusts remaining timeout passed to completion wait.
ext/dapr-ext-workflow/dapr/ext/workflow/aio/mcp.py	Implements the same retry-and-budget logic for async MCP connect().
ext/dapr-ext-workflow/tests/test_mcp_client.py	Adds tests for retry-on-transient-gRPC-error behavior for both sync and async clients.

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[codecov]

Codecov Report

❌ Patch coverage is 98.40000% with 2 lines in your changes missing coverage. Please review.
✅ Project coverage is 82.66%. Comparing base (bffb749) to head (58859e6).
⚠️ Report is 135 commits behind head on main.

Files with missing lines	Patch %	Lines
ext/dapr-ext-workflow/dapr/ext/workflow/aio/mcp.py	94.73%	1 Missing ⚠️
ext/dapr-ext-workflow/dapr/ext/workflow/mcp.py	96.55%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1062      +/-   ##
==========================================
- Coverage   86.63%   82.66%   -3.97%     
==========================================
  Files          84      146      +62     
  Lines        4473    14693   +10220     
==========================================
+ Hits         3875    12146    +8271     
- Misses        598     2547    +1949     

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