fix(cli): `emit` is advertised and implemented by three deploy adapters but never routed, so `deploy list` reports a command that does not exist

[rickylabs]

Summary

emit is advertised by three deploy adapters, implemented by them, and given a router description —
but it is not routed, so no netscript deploy <target> emit command exists. netscript deploy list reports an operation nobody can invoke.

Evidence

Verified at cd24e1679:

1. Advertised. packages/cli/src/kernel/adapters/aspire/aspire-compose-deploy-target.ts:64-71
   declares operations = ['plan', 'emit', 'up', 'down', 'status', 'logs']. The cloud and service
   deploy adapters advertise it too.

2. Implemented. aspire-compose-deploy-target.ts:95-97 implements the emit branch.

3. Described. target-deploy-command.ts OPERATION_DESCRIPTIONS carries
   emit: 'Emit deployment artifacts'.

4. Not routed. target-deploy-command.ts:15-23:

   const ROUTED_OPERATIONS: readonly DeployOperation[] = [
     'plan', 'up', 'down', 'status', 'logs', 'rollback', 'secrets',
   ];

   Subcommands are generated from ROUTED_OPERATIONS filtered by the adapter's advertised set
   (:42, :59), so an operation absent from ROUTED_OPERATIONS can never become a command
   regardless of what the adapter advertises. The public verb surface is the intersection, and
   emit is not in it.

Why it matters

The repo already states the correct convention for the opposite case:
service-deploy-target.ts:14-20 documents rollback/secrets as not advertised precisely so the
router does not expose them. emit is the inverse — advertised without being reachable — and
nothing enforces the invariant in either direction.

The user-visible consequence is netscript deploy list: it reports each target's advertised
operations, so it prints emit as available while netscript deploy <target> emit does not exist.
A reader who trusts deploy list gets a command-not-found. This also cost documentation work: a
docs pass counting advertised operations concluded the surface was six verbs and nearly shipped
that into the CLI reference; it is five.

Scope

Decide which side is right, then make the other match:

• if emit should be public, add it to ROUTED_OPERATIONS; or
• if it is internal (a plan implementation detail — note plan's own description is "Emit or
  preflight deployment artifacts", suggesting plan already covers it), stop advertising it and
  drop its OPERATION_DESCRIPTIONS entry.

Then close the class: a test asserting every advertised operation across every registered adapter
is routable, so advertise-without-route cannot recur silently. deploy list should report the
commands a user can run, not the adapter's internal capability set.

Boundaries

• docs(reference): publish-readiness paths still disagree with the plugin-core reference IA, and public README drift remains #1377 owns the docs statement of the verb surface and is corrected already — it documents the
  five reachable verbs. This issue is the source defect behind that discrepancy.
• Not a goal: changing what the adapters do, or the rollback/secrets non-advertisement, which is
  deliberate and correctly documented.

Acceptance criteria

• emit is either routable or no longer advertised — decision recorded on this issue.
• netscript deploy list reports only operations that resolve to a runnable command.
• A test fails when an adapter advertises an operation absent from ROUTED_OPERATIONS.
• Negative test: adding a fake advertised-but-unrouted operation to one adapter makes that test
  exit non-zero.

The negative test is drawn from the live defect, so the predicate is known to be satisfiable.

Provenance

Found by the 0.0.6 documentation-lane authoring pass for #1377 while verifying the deploy verb
surface against the command tree rather than against the adapter's operations array.