feat(runtime): invoke an operation with a positional argument list

[devin-ai-integration]

What and why

Context.InvokeOperation bound arguments by name only, and %invoke refused anything not written <p>=<expr>. An invocation in the model already binds positionally, so the two surfaces disagreed with each other and with the spec.

type OperationArguments struct {
    Positional []Value
    Named      map[string]Value
}
func (ctx *Context) InvokeOperationWith(inst *Instance, name string, args OperationArguments) (map[string]Value, error)
func (ctx *Context) InvokeOperation(inst, name, args map[string]Value) // now delegates: OperationArguments{Named: args}

• A positional list binds to semantics.Model.SignatureParametersOf(op) — signatureOf's effective in/inout parameters in signature order, out and result excluded — so a trailing defaulted parameter may be omitted, an inout takes a position and comes back as a result, and an out takes none. No second binder: this is the same signature an InvocationExpression is bound to.
• operationOf now collects every same-named member and, when there are several, selects through semantics.Model.SelectAmongArguments (the evaluator's overload selection), so two calcs scaled(factor) / scaled(factor, offset) are told apart by arity.
• Typed refusals: ErrMixedArguments (KerML: an ArgumentList is positional or named, never both), ErrOperationArity for a surplus positional, ErrUnboundParameter unchanged for a missing required one.
• REPL: %invoke <object> <op> [<expr>... | <p>=<expr>...] via a new parseInvokeArguments; a mixed list and a parameter named twice are refused before the object is resolved (so a rejected command still materializes nothing). The shared splitArgs/continuesExpr gained one rule — a <name>=… fragment always starts a new argument — so 1 n=2 no longer glues into one unparsable token; %calc/%analysis keep their existing named-argument refusal.
• The gRPC/proto surface and the Python client expose no operation invocation, so nothing there changed.

Shared plumbing touched: repl/meta.go continuesExpr (one added clause) and semantics/binding.go (new exported SignatureParametersOf adapter over signatureOf).

Specification basis

KerML 1.0 §8.2.5.8.3 (ArgumentList is a PositionalArgumentList or a NamedArgumentList) and §8.4.4.9.5 (a positional list binds the behavior's parameters in declaration order). Extends the Classifier Behaviors invocation row in docs/project/spec-compliance.md; the "Operation invocation with positional arguments" bullet leaves "Major Features Not Implemented"; roadmap E6 recorded as landed.

How it was verified

• runtime/classifier_behavior_test.go:TestInvokeOperationWithPositionalArguments — defaulted trailing parameter, inout, out, arity-resolved overloads, fewer/surplus/mixed lists, named out.
• New runtime/robustness_positional_invoke_test.go (TestRuntimeRobustnessPositionalInvoke).
• repl/classifier_behavior_test.go:TestInvokeBindsPositionalArguments, :TestInvokeReportsItsFailureModes (mixed, surplus, twice-named); object_args_test.go malformed-command cases extended.
• go build ./..., go vet ./..., gofmt -l . empty, go test ./... green; training and pilot corpus gates green with corpora downloaded; scripts/changelog.py check and scripts/check-doc-ids.py clean.

Checklist

• make test and make lint pass locally
• Tests added or updated for the change
• Documentation extended where it already covers the surface (see CONTRIBUTING.md)
• Changelog entry added as changes/unreleased/<slug>.<section>.md, not as an edit to CHANGELOG.md
• baselines regenerated and make docs-counts run if a gate count moved (compliance rows need nothing: the census is counted at docs build)
• No internal work-item labels (waves, slices, F4, K5) in the body, docs, or changelog

[devin-ai-integration]

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