V0316 differences from V0306:
- Use `<|marker_N|><|marker_N|>` instead of `NO_EDITS`
- All intermediate markers are now emitted (should be more friendly to
speculative decoding)
- No newline padding around marker tags
- No git conflict markers; we now use SeedCoder's EOS tag instead

V0317 is like V0316, but marker numbers are relative to the cursor block
(`<|marker-2|> ... -1 ... -0 ... +1 ... <|marker+2|>`)

Release Notes:

- N/A