fix(order-stream): preserve Redshift telemetry field compatibility

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Summary

• Add migration 005 to align request_completions with the current broker telemetry payload.
• Expose committed_to_application_proof_duration_secs and actual_total_proving_time_secs.
• Preserve proving_duration_secs and actual_proving_time_secs as compatibility aliases.
• Fall back to legacy JSON keys so telemetry ingested before migration 3 remains queryable.
• Remove reliance on the obsolete preflight_cache_hit field.
• Extend the Redshift telemetry integration test to validate the new fields and aliases.

Context

Migration 002 still referenced fields that are no longer emitted by the current Rust telemetry structs. Migration 003 corrected the schema, but removed historical completion column names that may still be used by dashboards and BI queries.

This migration is intentionally additive and does not modify already-applied migrations.

Testing

• cargo fmt --all -- --check
• git diff --check
• RISC0_SKIP_BUILD_KERNELS=1 RISC0_SKIP_BUILD=1 cargo test -p order-stream --test telemetry --no-run
• RISC0_SKIP_BUILD_KERNELS=1 RISC0_SKIP_BUILD=1 cargo test -p order-stream --test telemetry telemetry_end_to_end -- --nocapture

The Redshift end-to-end assertions were compiled successfully. The live Redshift test was skipped locally because ORDER_STREAM_URL and Redshift credentials were not configured.

[zloglevel]

@capossele Could you please take a look when you have a chance? Thanks!