Option C implementation: single namespace with composable file tables.
Batch jobs are sessions with a reduced file set — the directory
contents declare the capability.
- core: SessionStore absorbs BatchStore; s/new detects batch format
- 9p: /b/ removed entirely; all routing through /s/
- scripts/b/* moved to scripts/s/*; paths updated
- subagent_spawn, optimize: /b/q -> /s/q
- scripts/b/ removed
Levi Neely