Adopt the component declaration in in-repo generative process configs

[ealt]

Follow-up to the generative-process instantiation work
(docs/design/generators_instantiation.md §9 Q6).

Context

Run management now discovers a generative process two ways:

1. Namespace fast path — _target_ starts with simplexity.generative_processes.
2. Declaration — the config section sets component: generative_process

Path 2 exists because a process vendored from generators lives in the consumer's namespace and cannot
be recognized from its import path. Path 1 was retained deliberately so that the 11 in-repo process
configs, and the 60+ open branches that touch them, needed no changes.

The follow-up

Under the accepted direction (simplexity becomes a runner; processes live in consumers), the
namespace path is transitional: eventually every process config declares itself and the prefix test
retires. Adding component: generative_process to the in-repo configs makes the intent uniform and
lets the prefix path eventually be deleted rather than carried indefinitely.

The configs:

tests/end_to_end/configs/generative_process/
  mess3.yaml, rrxor.yaml, nonergodic_example.yaml,
  unified_chain_example.yaml, unified_chain_3mess3_2tomq.yaml,
  unified_independent_example.yaml, unified_independent_example_crazy.yaml,
  unified_symmetric_example.yaml, unified_transition_coupled_example.yaml,
  unified_transition_and_emission_coupled_example.yaml

Declaration is additive and already tested as harmless for simplexity targets
(test_declaring_a_simplexity_process_is_harmless), so this is a mechanical one-line-per-file change.

Why it was deferred

Purely churn against in-flight branches — several open branches carry process work
(adam/factor_tree, adam/hidden-factors, adam/producted-generator*, casper/*) and touching
every process config invites merge conflicts for no immediate functional gain. Better done once
those have landed, or deliberately timed.

Retiring the prefix path itself is a separate, later step and should not happen while any consumer
still relies on it.