Fix NFS shares never mounting on lxc-docker

Two compounding bugs, confirmed live on the running lxc-docker
container (vmid 102 on pve.sweet.home):

1. x-systemd.automount never works inside any Linux container --
   systemd logs "Starting of <unit>.automount unsupported" for every
   share and never mounts them. modules/docker/mount-data.nix and
   modules/raspi/mount-data.nix now key off config.boot.isContainer
   (set true by nixpkgs' proxmox-lxc.nix) to mount eagerly with
   `nofail` there instead, while VM-based docker targets keep automount
   unchanged.

2. The container's Proxmox `features` never included `mount=nfs`, so
   AppArmor blanket-denies the nfs/rpc_pipefs mount syscalls NFS
   needs ("permission denied"). scripts/env.sh's
   PROXMOX_DEFAULT_LXC_FEATURES now includes mount=nfs;nfs4 for future
   lxc-* containers -- the semicolon required quoting the --features
   value in create-proxmox-resource.sh's remote pct-create command,
   since it's sent as a raw string for the remote shell to parse and an
   unquoted `;` would be read as a command separator.

The already-running container needs a matching `pct set --features`
plus a restart to pick this up -- that's an operator step outside this
repo.

modules/docker/mount-data.nix

@@ -1,5 +1,15 @@
 { config, lib, pkgs, vars, ... }:
 
+let
+  # `x-systemd.automount` never works inside a Linux container (LXC
+  # included, regardless of privilege) -- confirmed live on lxc-docker:
+  # systemd logs "Starting of <unit>.automount unsupported" for every
+  # share and never mounts them. Mount eagerly there instead, with
+  # `nofail` so a boot with the NFS server unreachable doesn't hang
+  # (the VM platforms rely on automount itself to get that same
+  # non-blocking behavior, so they don't need `nofail` too).
+  automountOpts = if config.boot.isContainer then [ "nofail" ] else [ "x-systemd.automount" ];
+in
 {
   fileSystems = {
     ${vars.nfsShares.dockerConfig.mountpoint} = {
@@ -9,9 +19,8 @@
       options = [
         "nfsvers=4.2"
         "_netdev"
-        "x-systemd.automount"
         "noatime"
-      ];
+      ] ++ automountOpts;
     };
 
     ${vars.nfsShares.dockerDatabases.mountpoint} = {
@@ -21,9 +30,8 @@
       options = [
         "nfsvers=4.2"
         "_netdev"
-        "x-systemd.automount"
         "noatime"
-      ];
+      ] ++ automountOpts;
     };
 
     ${vars.nfsShares.dockerVolumes.mountpoint} = {
@@ -33,9 +41,8 @@
       options = [
         "nfsvers=4.2"
         "_netdev"
-        "x-systemd.automount"
         "noatime"
-      ];
+      ] ++ automountOpts;
     };
 
     ${vars.nfsShares.nextcloudData.mountpoint} = {
@@ -45,9 +52,8 @@
       options = [
         "nfsvers=4.2"
         "_netdev"
-        "x-systemd.automount"
         "noatime"
-      ];
+      ] ++ automountOpts;
     };
 
     ${vars.nfsShares.raspiVolumes.mountpoint} = {
@@ -57,9 +63,8 @@
       options = [
         "nfsvers=4.2"
         "_netdev"
-        "x-systemd.automount"
         "noatime"
-      ];
+      ] ++ automountOpts;
     };
   };
 }