## Why

Run currently persists and uploads one HTTP log batch for every captured output line. High-volume startup output can create thousands of pending requests faster than the five-second uploader window can acknowledge them, leaving the management terminal far behind the supervised process.

## What Changes

- Coalesce contiguous pending entries from the same Run log stream into bounded durable upload batches.
- Drain available log backlog continuously within bounded upload work so current output reaches the platform promptly without blocking control, job, or artifact channels.
- Preserve per-stream sequence continuity, checksums, retry retention, and acknowledgement semantics when a batch is rebuilt or retried.

## Capabilities

### New Capabilities

- `run-log-batch-upload`: Run-side durable aggregation and bounded delivery of supervised-process log streams.

### Modified Capabilities

- None.

## Impact

- Affects `run/spool` pending-log representation and flush behavior, plus `run/runtime` process-log spooling and uploader scheduling.
- Does not change platform API routes, browser contracts, game-specific lifecycle behavior, or artifact/control/job channels.