fix(env): hand a swarm env value to the container verbatim

_passthrough_swarm quoted and escaped any value containing whitespace,
which contradicts the contract stated at the top of the same module:
docker stack deploy does not strip outer quotes, so the value reaches the
container with them.

Ansible's to_json emits the default ", " separators, so AGENT_PLATFORMS
always carried spaces and arrived as "{\"hermes\": ...}". json.loads then
returned a str rather than a mapping, and sorted(PLATFORMS) in the broker
iterated its characters: the broker advertised one model per character and
never hermes or openclaw, which is why Open WebUI's model list held neither
and the agent-broker specs failed before reaching a completion. The same
encoding mangled AGENT_CONSTRAINT, whose placement expression would have
failed once an agent was reachable.

The branch existed for the opposite consumer: test.env is sourced by bash,
where KEY=one two leaves the variable unset under set -u. Quoting is the
wrong instrument for that, because one filter cannot serve both contracts
keyed on DEPLOYMENT_MODE alone. Both values that join on a space now join
on a comma and their consumers split on one, so no rendered env value needs
quoting to survive the shell.

Two unit tests asserted the quoting while a sibling in the same class
asserted that swarm does not escape a double quote; the pair could not both
hold. They are replaced by one test that renders real JSON and checks the
container receives a mapping. The lint that flags a space-joined value no
longer accepts dotenv_quote as the remedy, since in swarm it no longer
quotes, and its message names the comma instead.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

tests/unit/python/plugins/filter/test_dotenv_quote.py

@@ -94,14 +94,14 @@ class TestDotenvQuoteModeAware(unittest.TestCase):
     def test_swarm_non_string_is_stringified(self):
         self.assertEqual(self._render(42, mode="swarm"), "42")
 
-    def test_swarm_quotes_value_with_interior_whitespace(self):
+    def test_swarm_passes_a_value_with_spaces_through_unchanged(self):
         self.assertEqual(
-            self._render("My Org Helpdesk", mode="swarm"), '"My Org Helpdesk"'
+            self._render('{"hermes": {"group": "/x"}}', mode="swarm"),
+            '{"hermes": {"group": "/x"}}',
+            "swarm delivers the value verbatim, so quoting it makes the "
+            "container read the quotes as part of the JSON and parse a string",
         )
 
-    def test_swarm_whitespace_value_escapes_quotes_not_dollars(self):
-        self.assertEqual(self._render('a "b" $c', mode="swarm"), '"a \\"b\\" $c"')
-
     def test_compose_mode_quotes_like_default(self):
         self.assertEqual(self._render("abc", mode="compose"), '"abc"')
         self.assertEqual(self._render("$ecret", mode="compose"), '"$$ecret"')