fix(bag): stop infinite Range re-fetch loop when loading remote .bag files

[joaner]

Summary

• Remote .bag loading called @foxglove/rosbag's Filelike.size() synchronously internally (this._file.size() - fileOffset, never awaited), but bag.worker.ts's remote adapter exposed an async/BigInt size(). The un-awaited subtraction silently became NaN, which CachedFilelike can never mark as satisfied — it kept re-deriving and re-fetching the same ~50MiB block forever while Bag.open() never resolved.
• Root-cause fix: resolve the real byte count once up front and expose a synchronous size(), matching the library's real Filelike contract; import that type directly (dropping an unsafe as cast) so a future mismatch is a compile error again.
• Defense in depth in CachedFilelike: reject non-finite/negative offsets and lengths at the read()/prefetch() entry points instead of silently enqueueing unsatisfiable requests, and bound the connection-error retry count so a persistently (but not rapidly) failing fetch can no longer retry forever.
• Bump to v1.7.9.

Test plan

• npm run lint
• npm test (666 tests, incl. new regression coverage in CachedFilelike.test.ts and remoteBagReadable.test.ts)
• npx tsc -b --noEmit
• Manual end-to-end repro against a real 480MB rgbd_dataset_freiburg1_xyz.bag served locally over HTTP Range: before the fix, initialize() hung past 12s and emitted a literal Range: bytes=NaN-NaN request; after the fix it resolves in ~500ms with the correct topic list and no duplicate/invalid Range requests.
• CI (lint / build / test / e2e)