unify s/ and b/ namespaces: batch jobs now live under s/

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

9p

@@ -1 +1 @@
-Subproject commit 9f5286c8b2f974906eb5c0dfee5bebee270a5bb5
+Subproject commit 8d5be7212fb9abcf540c946b4690831ac226fd3e

core

@@ -1 +1 @@
-Subproject commit 8f856ea186d558597b5d8d3b0a2320ae89d73065
+Subproject commit 10dd4ee82fa0b0aeb1bd3101c21b13e856b9b142

scripts/s/cleanup

@@ -1,10 +1,10 @@
 #!/usr/bin/env bash
-# b/cleanup: remove all batch jobs with state "done".
+# s/cleanup: remove all batch jobs with state "done".
 set -euo pipefail
 
 OLLIE=${OLLIE:-$HOME/mnt/ollie}
 
-for job in "$OLLIE"/b/*/; do
+for job in "$OLLIE"/s/*/; do
     [ -d "$job" ] || continue
     state=$(cat "$job/state" 2>/dev/null | tr -d '[:space:]') || continue
     case "$state" in

scripts/s/job

@@ -1,5 +1,5 @@
 #!/usr/bin/env bash
-# b/job: non-interactive ollie query via b/ namespace.
+# s/job: non-interactive ollie query via s/ namespace.
 #
 # Usage: oq [flags] [prompt...]
 #        echo "prompt" | oq [flags]
@@ -92,7 +92,7 @@ cwd=${cwd:-$(pwd)}
     printf 'parallel=%s\n' "$parallel"
     printf -- '---\n'
     printf '%s\n' "$prompt"
-} > "$MOUNT/b/new" || die "failed to submit job"
+} > "$MOUNT/s/new" || die "failed to submit job"
 
 if [ "$bg" -eq 1 ]; then
     for i in $(seq 0 $((parallel - 1))); do
@@ -109,7 +109,7 @@ if [ "$parallel" -gt 1 ]; then
     pids=()
     for i in $(seq 0 $((parallel - 1))); do
         id="${name}-${i}"
-        B="$MOUNT/b/$id"
+        B="$MOUNT/s/$id"
         (
             exec 3< "$B/statewait"
             while true; do
@@ -128,7 +128,7 @@ if [ "$parallel" -gt 1 ]; then
                              echo 1 > "$abort"
                              for j in $(seq 0 $((parallel - 1))); do
                                  jid="${name}-${j}"
-                                 [ "$jid" != "$id" ] && rm -r "$MOUNT/b/$jid" 2>/dev/null || true
+                                 [ "$jid" != "$id" ] && rm -r "$MOUNT/s/$jid" 2>/dev/null || true
                              done
                          fi
                          [ "$keep" -eq 0 ] && rm -r "$B" 2>/dev/null || true
@@ -153,7 +153,7 @@ if [ "$parallel" -gt 1 ]; then
     for pid in "${pids[@]}"; do wait "$pid" || rc=1; done
 else
     id="${name}-0"
-    B="$MOUNT/b/$id"
+    B="$MOUNT/s/$id"
 
     exec 3< "$B/statewait"
     while true; do

scripts/s/q

@@ -1,5 +1,5 @@
 #!/usr/bin/env bash
-# b/q: foreground one-shot query; output goes to stdout.
+# s/q: foreground one-shot query; output goes to stdout.
 for _arg; do
     [ "$_arg" = "-help" ] && cat <<'EOF' && exit 0
 usage: q [flags] [prompt...]

scripts/s/sched

@@ -1,5 +1,5 @@
 #!/usr/bin/env bash
-# b/sched: submit a background job; prints the b/ path for each job.
+# s/sched: submit a background job; prints the b/ path for each job.
 for _arg; do
     [ "$_arg" = "-help" ] && cat <<'EOF' && exit 0
 usage: sched [flags] [prompt...]
@@ -22,5 +22,5 @@ if [ $# -eq 0 ] && [ -t 0 ]; then
 fi
 OLLIE=${OLLIE:-$HOME/mnt/ollie}
 "${0%/*}/job" -bg "$@" | while IFS= read -r id; do
-    [ -n "$id" ] && printf '%s/b/%s\n' "$OLLIE" "$id"
+    [ -n "$id" ] && printf '%s/s/%s\n' "$OLLIE" "$id"
 done

scripts/u/optimize

@@ -47,7 +47,7 @@ fi
 
 [ -z "$prompt" ] && { printf 'optimize: empty prompt\n' >&2; exit 1; }
 
-Q="${0%/*}/../b/q"
+Q="${0%/*}/../s/q"
 
 c_flags=()
 j_flags=()