feat(broker): adopt running-process v1 broker session for the daemon wire

[zackees]

Summary

Migrates the clud daemon's broker frame lane onto the frozen v1 running-process adoption API and bumps running-process 4.2.0 → 4.3.0. Implements zackees/running-process#436.

• WireMode { JsonLegacy, ProstV1 } selector at the daemon boundary. RUNNING_PROCESS_DISABLE=1 forces json-legacy + the direct TCP endpoint; every other launch uses prost-v1. Both arms decode into the same internal DaemonRequest/DaemonResponse model via the existing wire_prost adapters.
• BrokerSession::adopt replaces the raw connect_to_backend/FrameClient path. Hello sends service_name="clud", protocol 1..=1, client_lib_name="running-process", and wanted_version = the clud daemon version. clud payloads still ride the 0x7C4C frame lane; on any miss the call degrades to the authoritative legacy JSON-over-TCP wire.
• Typed RefusalKind classification (VersionUnsupported/VersionBlocked/ServiceUnknown/RateLimited/ShuttingDown/Other) logs the cause of a broker refusal before falling back, instead of silently swallowing it.
• ServiceDefinitionBuilder builds the SHARED_BROKER definition declaring min_version 2.0.0 and a consumer=clud label; CacheManifestBuilder publishes the runtime/lock/config/log roots at daemon bringup.
• Diagnostics: clud daemon running-process [--json] now surfaces wire_mode, min_version, and adopts_broker_session.

The RUNNING_PROCESS_FAKE_BACKEND seam moved behind running-process's off-by-default test-seams feature in 4.3.0 (upstream #433 R4). The seam test enables it via a dev-dependency only — Cargo unifies that into cargo test but not into cargo build --bin clud, so the production binary stays seam-free per the upstream rule.

Test plan

• cargo test -p clud --lib daemon::rp_broker — 10/10 pass (against published 4.3.0), incl. new wire_mode_select_maps_the_disable_hatch, publish_cache_manifest_records_clud_roots_and_round_trips, strengthened servicedef test (min_version 2.0.0 + consumer label), and the now-fixed fake_backend_seam_overrides_cached_endpoint.
• cargo test -p clud --lib daemon:: — 120/120 pass (incl. all wire_prost JSON/prost parity tests).
• bash lint — clean (cargo fmt --check, clippy -D warnings, ruff).
• Production cargo build --bin clud verified seam-free (cargo tree -e normal shows no test-seams edge).
• Full CI matrix (Windows/Linux/macOS x86+ARM) — to be confirmed on this PR.

Note: one unrelated timing-flaky test (process_tree::kill_tree_terminates_real_descendant_on_windows) tripped its threshold under serial full-suite load on a cold cache; it passes in isolation and is unrelated to these changes.

Refs zackees/running-process#436

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