fix(upstream:PLA-688): stop non-retryable and write-path retries

[0x666c6f]

Summary

• fix retry policy fallthrough for network-scope non-retryable errors
• block retry attempts for non-retryable write methods even on error-only (result=nil) paths
• add regression tests for both cases in upstream/failsafe_test.go

Changes

• in createRetryPolicy, return false when IsRetryableTowardNetwork(err) is false
• centralize request extraction from result/error/context via extractRetryRequest
• use extracted request for write-method retry guard and missing-data retry-empty check
• add tests:
  • NetworkScope_NonRetryableTowardNetwork_NoRetry
  • WriteMethodInContext_ErrorOnlyPath_NoRetry

Linear

• TICKET: https://linear.app/morpho-labs/issue/PLA-688/erpc-retry-correctness-hardening-non-retryable-fallthrough-write