Stacks: one machine, one set of files; default home is <data dir>/stacks

The hub no longer probes a node's Docker on tcp :2375, holds compose files
for a node, or runs compose against another machine's Docker. hubStacks,
nodeDocker, taskOnHub and the hub-side /api/nodes/{node}/docker/... routes
are gone; the generic node proxy hands those requests to the node's own
Ham Lab. Stack.remote / held_by and compose.Spec.Remote are removed.

New stacks default to <data dir>/stacks on every machine. Folders with two
or more deployed stacks are still offered, after it, never as default.
The ~/stacks fallback is gone. A missing home is skipped without a sudo find.

A schedule saved earlier with a tcp target is refused with a message
instead of being run against this machine's Docker.

PORTABILITY.md 3.1, 3.2, 3.3 and 9.2 done; 3.5 checked, no change needed.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

web/src/Docker.tsx

@@ -355,7 +355,7 @@ function StackDetail({ name, startTask, onBack, onChanged, onDuplicate }: { name
     <div className="svc-detail">
       <CloseBtn onClick={onBack} />
       <div className="svc-head"><button className="btn back" onClick={onBack}>‹ Back</button><span className={'sdot ' + (st.containers.length === 0 ? '' : st.running === st.containers.length ? 'ok' : st.running ? 'warn' : 'bad')} /><span className="dname">{st.name}</span><span className="muted small">{st.running}/{st.containers.length} running</span></div>
-      <div className="muted small mono" style={{ overflowWrap: 'anywhere' }}>{file === 'env' ? (st.host_file.replace(/[^/]+$/, '') + '.env') : (st.host_files?.[file] ?? st.host_file)}{st.held_by && <span className="muted"> · kept on <b>{st.held_by}</b>, deployed to this machine over {st.remote}</span>}{st.via && <span className="muted"> · compose runs inside <b>{st.via}</b>, as it was deployed</span>}{st.has_env && ' · has a .env beside it'}</div>
+      <div className="muted small mono" style={{ overflowWrap: 'anywhere' }}>{file === 'env' ? (st.host_file.replace(/[^/]+$/, '') + '.env') : (st.host_files?.[file] ?? st.host_file)}{st.via && <span className="muted"> · compose runs inside <b>{st.via}</b>, as it was deployed</span>}{st.has_env && ' · has a .env beside it'}</div>
       {((st.host_files?.length ?? 0) > 1 || st.has_env) && <div className="chips" title="this stack is deployed from several files, in this order; Deploy uses all of them">{st.host_files!.map((f, i) => <button key={f} className={'chip' + (i === file ? ' on' : '')} onClick={async () => { if (dirty && !(await askYes('Discard unsaved changes to this file?', 'Discard'))) return; setFile(i) }}>{f.split('/').pop()}</button>)}{st.has_env && <button className={'chip' + (file === 'env' ? ' on' : '')} title="the .env beside the compose file: variables compose substitutes" onClick={async () => { if (dirty && !(await askYes('Discard unsaved changes to this file?', 'Discard'))) return; setFile('env') }}>.env</button>}</div>}
       {file === 'env' && !reveal ? <div className="env-masked"><pre className="editor stack-editor">{maskEnv(text)}</pre><button className="btn" onClick={() => setReveal(true)}>Reveal and edit</button></div> :
       <CodeEditor className="stack-editor" language={file === 'env' ? 'env' : 'yaml'} value={text} onChange={setText} />}
@@ -447,7 +447,7 @@ export default function Docker() {
           {shownTab === 'stacks' && (stacks ?? []).map((st) => (
             <div key={st.name} className={'svc-row' + (st.name === selStack ? ' active' : '')} onClick={() => st.editable ? setSel('stack:' + st.name) : toast(st.note ?? 'not editable here', 'info')}>
               <span className={'sdot ' + (st.containers.length === 0 ? '' : st.running === st.containers.length ? 'ok' : st.running ? 'warn' : 'bad')} />
-              <div className="svc-name"><div className="n">{st.name}</div><div className="d">{st.editable ? (st.held_by ? `on ${st.held_by}: ` : '') + st.host_file : st.note}</div></div>
+              <div className="svc-name"><div className="n">{st.name}</div><div className="d">{st.editable ? st.host_file : st.note}</div></div>
               <div className="svc-state">{st.containers.length === 0 ? 'not deployed' : `${st.running}/${st.containers.length}`}{!st.editable && <><br />read-only</>}</div>
             </div>
           ))}