fix(upgrade): quiesce rejected bindings before rollback

[fuller-stack-dev]

Summary

• quiesce a rejected active binding before restoring an upgrade snapshot, even
  when the target reused an existing named runtime and mutated no runtime tree
• prevent a backoff/retry process from rewriting managed-plugin
  node_modules/openclaw peer links after source-state restoration
• extend the named-runtime rollback regression to cover four managed plugins,
  retained/missing/rejected links, restored service binding, and gateway RPC
  readiness

Root cause

rollback_upgrade_locked quiesced only when runtime bytes had changed. A switch
to an already-installed named runtime changes the published binding without
adding mutated_runtime_names, so a rejected target in supervisor backoff could
remain able to mutate the environment while OCM restored the source snapshot.

Whole-root snapshot restoration already preserves these symlinks in a cold
fixture. A post-rollback repair phase would therefore be downstream and still
racy. The owner invariant is process exclusion: quiesce whenever rollback
changes runtime bytes or the active binding, before restoring source-owned
state.

Evidence

Base: 6a30e9063bcf85d1cba4c1c358ce6140e70fcf40

Head: f63f41af1638a3c03a6f6826d908b128f89d13ce

On unmodified canonical source, the active-service fixture completed rollback
with clickclack/node_modules/openclaw resolving to rejected runtime
2026.8.2 instead of restored runtime 2026.8.1.

On this head, the same fixture reports:

rollback proof: binding=2026.8.1 plugins=4 peerTarget=.../runtimes/2026.8.1/files/node_modules/openclaw gatewayRpc=ok channels=fixture-not-supported

The fixture verifies clickclack, codex, discord, and llama-cpp; exact
raw and resolved peer-link targets; one retained valid link; one removed link;
two rejected-runtime links; restored service binding; and deep gateway RPC
readiness. It does not configure real channels, so no channel-health claim is
made.

Validation

• cargo test --locked -- --test-threads=1
• cargo clippy --workspace --all-targets --all-features --locked -- -D warnings -A clippy::question_mark -A clippy::large_enum_variant -A clippy::too_many_arguments
• cargo +1.88.0 check --workspace --all-targets --locked
• cargo fmt --all -- --check
• source-blind red/base and green/head behavior validation
• focused cold-snapshot falsifier and rollback readiness/service controls
• shared autoreview: clean, no actionable findings

PRs #71, #72, and #73 and current main were checked before implementation.
This change does not add OpenClaw convergence retries or invoke a manual repair
command.

[fuller-stack-dev]

Landed via squash merge as f6dea9f7e90215964d8a5dfc25c841c71f298629 after all required checks passed.