fix: share smb client persist — write a real .automount unit

x-systemd.automount in a unit file's Options= is only honored when read
from /etc/fstab, so persisted mounts never armed an automount; the unit was
also static (no [Install]) so enable was a no-op. Result: after a reboot the
share sat inactive and the disk never mounted on access.

persist now writes both <name>.mount and <name>.automount units (the
automount with WantedBy=multi-user.target) and enables/starts the automount;
unpersist stops/disables/removes both units.

DOC/AGENT_Context_Project.md

@@ -604,7 +604,7 @@ Use conventional prefixes: `feat:`, `fix:`, `docs:`, `refactor:`, `chore:`
 | `bin/pos-network-scan` | 271 | Parallel ping sweep of CIDR |
 | `bin/pos-share-nfs-client` | 138 | Mount NFS shares (ephemeral or persistent systemd mount units) |
 | `bin/pos-share-nfs-server` | 134 | Manage the NFS kernel server (status, share/unshare exports, enable/disable) |
-| `bin/pos-share-smb-client` | 202 | Mount SMB/CIFS shares (ephemeral or persistent systemd mount units) |
+| `bin/pos-share-smb-client` | 217 | Mount SMB/CIFS shares (ephemeral or persistent systemd mount units) |
 | `bin/pos-share-smb-server` | 253 | Manage the Samba server (status, share/unshare exports, users, enable/disable) |
 | `bin/pos-share-usb-server` | 218 | USB Redirector server control (--ls, --share; prompts when args omitted) |
 | `bin/pos-ssh-load-keys` | 31 | Load all SSH keys into the agent |

DOC/POS.md

@@ -255,7 +255,7 @@ Subcommands that need input prompt interactively when args are omitted.
 | `pos share nfs server <cmd>` | `bin/pos-share-nfs-server` | Manage the NFS kernel server: `status`, `share <path> [client]`, `unshare <path>`, `list`, `reload`, `enable`, `disable` | Requires `nfs-kernel-server` (added to `preinstall.sh` PACKAGES). Exports live in `/etc/exports`; `share` is idempotent (replaces any existing line for the path) and runs `exportfs -ra`. Default client `*(rw,sync,no_subtree_check)` — the tool warns you to restrict it; help prints Tailscale CGNAT (`100.64.0.0/10`), WireGuard (`10.10.0.0/24`) and LAN examples. Mutating commands announce via `lib/notify.sh` |
 | `pos share nfs client <cmd>` | `bin/pos-share-nfs-client` | Mount and manage NFS shares: `mount <server:export> <local-dir>`, `unmount <local-dir>`, `list`, `persist <server:export> <local-dir>`, `unpersist <local-dir>` | Requires `nfs-common` (added to `preinstall.sh` PACKAGES). `persist` writes a systemd `.mount` unit (`systemd-escape --path --suffix=mount`) with `After=network-online.target` / `Wants=network-online.target` — mounts only once all interfaces are up, no fstab edits to break boot — then `daemon-reload` + `enable --now`. `unpersist` stops/disables/removes the unit. `mount`/`persist` announce via `lib/notify.sh` |
 | `pos share smb server <cmd>` | `bin/pos-share-smb-server` | Manage the Samba server: `status`, `share <path> [name] [--read-only|--guest|--users u1,u2]`, `unshare <name>`, `list`, `adduser <user>`, `deluser <user>`, `reload`, `enable`, `disable` | Requires `samba` (added to `preinstall.sh` PACKAGES). Shares are idempotent marker blocks (`# >>> pos-managed share: <name>` … `# <<< end pos-managed share`) in `/etc/samba/smb.conf` — hand edits outside the markers survive; `share` validates with `testparm` before applying and hot-reloads via `smbcontrol smbd reload-config`. Defaults rw + browsable; warns when unrestricted (guest or no `valid users`). `adduser`/`deluser` manage Samba accounts via `smbpasswd`. Mutating commands announce via `lib/notify.sh` |
-| `pos share smb client <cmd>` | `bin/pos-share-smb-client` | Mount and manage SMB/CIFS shares: `mount <//server/share> <local-dir> [user]`, `unmount <local-dir>`, `list`, `persist <//server/share> <local-dir> [user]`, `unpersist <local-dir>` | Requires `cifs-utils` (added to `preinstall.sh` PACKAGES). With a user you are prompted for the Samba password — one-shot mounts use a throwaway chmod-600 credentials file, `persist` keeps one at `/etc/samba/credentials/<name>` (chmod 600). `persist` writes a systemd `.mount` unit (`systemd-escape --path --suffix=mount`) with `x-systemd.automount` + `_netdev` — mounts on first access, never blocks boot — then `daemon-reload` + `enable --now`. `unpersist` stops/disables/removes the unit + credentials. `list` shows active mounts (`findmnt -t cifs`) **and** persistent units (as automount shares aren't mounted until first access, they'd otherwise be invisible). `mount`/`persist` announce via `lib/notify.sh` |
+| `pos share smb client <cmd>` | `bin/pos-share-smb-client` | Mount and manage SMB/CIFS shares: `mount <//server/share> <local-dir> [user]`, `unmount <local-dir>`, `list`, `persist <//server/share> <local-dir> [user]`, `unpersist <local-dir>` | Requires `cifs-utils` (added to `preinstall.sh` PACKAGES). With a user you are prompted for the Samba password — one-shot mounts use a throwaway chmod-600 credentials file, `persist` keeps one at `/etc/samba/credentials/<name>` (chmod 600). `persist` writes systemd `.mount` **and** `.automount` units (`systemd-escape --path --suffix=mount`) with `_netdev` — the automount defers the actual mount until first access, never blocks boot — then `daemon-reload` + `enable --now` the automount. `unpersist` stops/disables/removes both units + credentials. `list` shows active mounts (`findmnt -t cifs`) **and** persistent units (as automount shares aren't mounted until first access, they'd otherwise be invisible). `mount`/`persist` announce via `lib/notify.sh` |
 
 ### communication
 

DOC/howto/share.md

@@ -231,8 +231,9 @@ mounts use a throwaway chmod-600 credentials file, `persist` keeps one at
 `/etc/samba/credentials/<name>` (chmod 600) and references it from the unit.
 
 **Persistent mounts use systemd, not fstab.** `persist` writes a
-`/etc/systemd/system/<mnt-name>.mount` unit (`systemd-escape`) with
-`x-systemd.automount` + `_netdev`: the share is mounted **on first access**
+`/etc/systemd/system/<mnt-name>.mount` unit (**and** a matching
+`<mnt-name>.automount` unit, both `systemd-escape`d) with `_netdev`: the
+automount is enabled and armed, and the share is mounted **on first access**
 instead of at boot, so an unreachable SMB server can never hang boot (with
 fstab it could). `enable --now` arms the automount immediately.