QCDL signals: accept any group of qubits as one_to_all destinations

[qci-amos]

Part of splitting #71 into reviewable pieces. Independent of the other four.

The problem

QCDLModule.one_to_all was annotated and written for a Scope only, reaching
straight for destinations.qcdl_modules and destinations.scope_id. Passing
anything else — including scope.qcdl_modules, which is what the user guide
shows in places — raised AttributeError: 'list' object has no attribute 'scope_id'. Sending to a single qubit meant wrapping it in a Scope first.

The change

_as_modules normalizes the destinations into a list of modules, accepting a
Scope, a single QCDLModule, or a sequence of either, and deduplicating by
name while preserving order.

scope_id is only carried through when a Scope was actually passed: a bare
sequence has no identity of its own, so tagging its statements with someone
else's scope id would be a lie. That distinction is covered by a test.

A non-module destination, or an empty one, now raises QCDLUserError naming
the parameter, rather than surfacing as an AttributeError on an internal
attribute further down.

Compatibility

Purely widening — every call that worked before works unchanged and produces
the same statement.

Testing

pytest tests/ passes. tests/test_scope.py parameterizes over each accepted
destination form (scope, list, tuple, reversed list, single module, mixed,
repeated) and asserts the resulting qubit list, plus the scope_id rule and
the three rejection cases.

🤖 Generated with Claude Code

[codecov]

Codecov Report

❌ Patch coverage is 98.21429% with 1 line in your changes missing coverage. Please review.
✅ Project coverage is 90.26%. Comparing base (206a2d6) to head (f14aebf).
⚠️ Report is 3 commits behind head on main.

Files with missing lines	Patch %	Lines
dwave/gate/qcdl/components.py	94.44%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main      #74      +/-   ##
==========================================
+ Coverage   90.18%   90.26%   +0.08%     
==========================================
  Files          31       31              
  Lines        5317     5373      +56     
==========================================
+ Hits         4795     4850      +55     
- Misses        522      523       +1     

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