ci: fold parity into QA release validation (#74622)

Summary:
- The PR deletes the standalone `Parity gate` workflow, renames QA parity wording from gate to lane, routes docs toward QA/release validation, and adjusts the Docker E2E boundary guard for package-backed live lanes.
- Reproducibility: not applicable. as a CI/docs refactor. The high-confidence review path is static comparison of the repaired PR diff against current workflow/docs code plus exact-head check status.

ClawSweeper fixups:
- Included follow-up commit: ci: fold parity into QA release validation
- Ran the ClawSweeper repair loop before final review.

Validation:
- ClawSweeper review passed for head 3482654058.
- Required merge gates passed before the squash merge.

Prepared head SHA: 3482654058
Review: https://github.com/openclaw/openclaw/pull/74622#issuecomment-4359168336

Co-authored-by: Vincent Koc <vincentkoc@ieee.org>
Co-authored-by: clawsweeper <274271284+clawsweeper[bot]@users.noreply.github.com>

docs/reference/RELEASING.md

@@ -173,7 +173,7 @@ the maintainer-only release runbook.
   plugins.
 - Release checks now run in a separate manual workflow:
   `OpenClaw Release Checks`
-- `OpenClaw Release Checks` also runs the QA Lab mock parity gate plus the fast
+- `OpenClaw Release Checks` also runs the QA Lab mock parity lane plus the fast
   live Matrix profile and Telegram QA lane before release approval. The live
   lanes use the `qa-live-shared` environment; Telegram also uses Convex CI
   credential leases. Run the manual `QA-Lab - All Lanes` workflow with
@@ -443,7 +443,7 @@ package mechanics.
 
 Release QA Lab coverage includes:
 
-- mock parity gate comparing the OpenAI candidate lane against the Opus 4.6
+- mock parity lane comparing the OpenAI candidate lane against the Opus 4.6
   baseline using the agentic parity pack
 - fast live Matrix QA profile using the `qa-live-shared` environment
 - live Telegram QA lane using Convex CI credential leases