[AINode] Fix inference output TsBlock type

[CRZbulabula]

Description

Fix inference output type

DataNode declares CALL INFERENCE output schema as DOUBLE, but AINode serialized model tensors using their original dtype. For float32 outputs such as chronos2, this produced a FLOAT TsBlock column and clients calling getDouble() failed.

This PR converts inference outputs to torch.float64 before TsBlock serialization so the physical TsBlock column matches the DOUBLE result schema.

Tests

• Added coverage in AINodeSharedClusterIT to assert the output metadata type is DOUBLE and actually read values with ResultSet#getDouble("output").
• Verified AINode serde converts the manager output path to DOUBLE.
• Ran black .
• Ran isort --profile black .
• Ran mvn spotless:apply -pl integration-test -P with-integration-tests
• Ran mvn -pl integration-test -P with-integration-tests test-compile

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This PR has:

• been self-reviewed.
• added comments explaining the "why" and the intent of the code wherever would not be obvious for an unfamiliar reader.
• added integration tests.

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Key changed/added classes (or packages if there are too many classes) in this PR

• iotdb-core/ainode/iotdb/ainode/core/manager/inference_manager.py
• integration-test/src/test/java/org/apache/iotdb/ainode/it/AINodeSharedClusterIT.java

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 40.59%. Comparing base (75d6855) to head (861e50c).

Additional details and impacted files

@@             Coverage Diff              @@
##             master   #17766      +/-   ##
============================================
- Coverage     40.60%   40.59%   -0.01%     
  Complexity     2574     2574              
============================================
  Files          5179     5179              
  Lines        350271   350271              
  Branches      44790    44790              
============================================
- Hits         142228   142208      -20     
- Misses       208043   208063      +20     

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