refactor(databases): stream /files upload via SDK upload_stream

[zfarrell]

Migrates the streaming /files upload off the raw-HTTP helper onto the SDK's upload_stream (now with content_length, via hotdata-dev/sdk-rust#35), bridging the progress-wrapped blocking reader into an async byte stream on a dedicated no-timeout client. Closes #133.

[claude]

Clean migration. The blocking→async bridge handles back-pressure, receiver-drop, and read errors correctly, and with Content-Length set a mid-stream error aborts rather than truncating (no data-integrity risk). Auth/scope headers ride along via the cloned Configuration, and the no-timeout client is preserved on the SDK seam. Tests cover sized, chunked, and error-status paths, with the 5 MiB payload exercising channel back-pressure. The old raw-HTTP upload client and current_bearer are fully removed with no orphan references.

[sentry]

Codecov Report

❌ Patch coverage is 91.96429% with 9 lines in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
src/sdk.rs	95.37%	5 Missing ⚠️
src/databases.rs	0.00%	4 Missing ⚠️

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[claude]

Clean migration off the raw-HTTP upload helper onto the SDK's upload_stream. The blocking→async bridge is correct (bounded back-pressure, receiver-drop and read-error paths both terminate cleanly), the no-timeout client preserves auth/scope headers via the cloned Configuration, error mapping reuses ApiError::from_sdk, and the removed helpers leave nothing orphaned. Tests cover sized, chunked, and error-status paths with a payload that exercises chunk-spanning and channel back-pressure.