v3.22.3: the mismatch on_fail, the self-healing move, the pruning reconciliation

Three test-management issues:

- an expectation whose command type did not match the pending command
  hard-coded level 'error', so on_fail "warning" tolerated "no command
  pending" but not "a different command is pending".  The check now honours
  the step's on_fail - the tolerant form for "the applet either asks X or
  does Y" (the mismatched command is still fetched and answered).
- moving a script between suites could answer 500 and leave two owners:
  _test_script_move detached only from the suite named by the script's
  suite_id and appended to the target unconditionally, so a duplicate
  listing or a stale suite_id (a hand edit, an interrupted move) collided
  on the attach.  It now detaches from every suite that lists the script,
  takes the on_fail from the explicit owner (suite_id if that suite lists
  it, else the first lister), updates the script first (a refused
  validation changes nothing) and re-attaches with a prune; the same-suite
  no-op only applies when the target really is the only lister.
- reconcile_scripts_to_suites() now prunes duplicate listings to the
  explicit owner (it only adopted before), so those states self-heal at
  startup and after a bundle import; the "Imported scripts" suite is only
  created when there are orphans.

Docs: the bundle-import note (importing into the source store duplicates
the suite and its scripts - the round-trip is not idempotent) and the
expectation on_fail clarification.
Tests: 839 frontend + 818 Python; sw cache simple-v407.

frontend/sw.js

@@ -1,4 +1,4 @@
-const CACHE = 'simple-v406';
+const CACHE = 'simple-v407';
 const URLS = [
   'index.html',
   'help.html',