fix(prometheus, syslog): a target or pattern pauses with a Pause/Resume button, not an "on" tick box in its form (#6419)

Monitors, schedules and maintenance plans already pause with a
Pause/Resume button and say "Paused" where they're listed. Prometheus
targets and syslog patterns only had a tick box inside the edit form,
so a target refused by its endpoint couldn't be stopped from its page.

- Both get a Pause/Resume button (target page and list; patterns list)
  posting to /toggle, recorded in the audit log, and a Paused badge.
- The forms lose the tick box. A new one starts running; an edit keeps
  whether it is paused.
- A target's "off" state is now "paused", in its pages and MCP tools.
  A resumed target reads "not scraped yet" until its next scrape, and its
  counter rates start over.

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

tests/integration/test_syslog.py

@@ -372,12 +372,13 @@ def test_patterns_page_adds_edits_and_removes_and_a_rename_moves_counts(app):
         assert "at least one phrase" in await refused.get_data(as_text=True)
         made = await admin.post("/plugins/syslog/patterns/new", headers=csrf,
                                 form={"name": "Quota full", "phrases": "100%\nquota", "max_severity": "4",
-                                      "window_minutes": "60", "enabled": "on"})
+                                      "window_minutes": "60"})
         assert made.status_code == 302
         async with app.db_sessionmaker() as s:
             rows = {p.key: p for p in (await s.execute(select(models.SyslogPattern))).scalars()}
         assert set(rows) == {"nfs", "quota_full"}
         assert (rows["quota_full"].phrases, rows["quota_full"].max_severity) == (["100%", "quota"], 4)
+        assert rows["quota_full"].enabled                                   # a new pattern counts
         assert rows["nfs"].phrases[0] == "nfsd:"
 
         await patterns.record_counts(app, now)
@@ -391,13 +392,24 @@ def test_patterns_page_adds_edits_and_removes_and_a_rename_moves_counts(app):
         )).get_data(as_text=True)
         assert '<option value="syslog" selected>' in rule_form          # aimed at the pattern's count
 
-        # Edited: the key, and so the metric, stay.
-        edited = await admin.post(f"/plugins/syslog/patterns/{rows['quota_full'].id}/edit", headers=csrf,
+        # Paused from the list (#6419), not from a tick box in the form.
+        quota = rows["quota_full"].id
+        assert (await admin.post(f"/plugins/syslog/patterns/{quota}/toggle", headers=csrf)).status_code == 302
+        page = " ".join((await (await admin.get("/plugins/syslog/patterns")).get_data(as_text=True)).split())
+        assert '<span class="badge badge-dim">Paused</span>' in page and ">Resume</button>" in page
+        form_page = await (await admin.get(f"/plugins/syslog/patterns/{quota}/edit")).get_data(as_text=True)
+        assert 'name="enabled"' not in form_page
+
+        # Edited: the key, and so the metric, stay, and so does the pause.
+        edited = await admin.post(f"/plugins/syslog/patterns/{quota}/edit", headers=csrf,
                                   form={"name": "Quota", "phrases": "quota", "window_minutes": "15"})
         assert edited.status_code == 302
         async with app.db_sessionmaker() as s:
-            p = await s.get(models.SyslogPattern, rows["quota_full"].id)
+            p = await s.get(models.SyslogPattern, quota)
             assert (p.key, p.name, p.enabled, p.max_severity) == ("quota_full", "Quota", False, None)
+        assert (await admin.post(f"/plugins/syslog/patterns/{quota}/toggle", headers=csrf)).status_code == 302
+        async with app.db_sessionmaker() as s:
+            assert (await s.get(models.SyslogPattern, quota)).enabled
 
         # A renamed source takes its counts with it.
         renamed = await admin.post(f"/plugins/syslog/sources/{src_id}/edit", headers=csrf,