docs(releases): expand v15 page to full 14.8→15.0→15.1 backend + Console coverage

The previous revision under-covered the line in three ways, now fixed:

1. 15.0.0 was missing everything outside the ADR-0095 theme from the
   14.8.0..15.0.0 range: the strict view/page schema BREAKING change
   (ADR-0089 D3a, #2943) with its migration, the per-row import automation
   chain + skipAutomations + runAutomations-default-ON behavior change
   (#2922), the sys_position/sys_capability system-row write guardrail
   (#2930), the bidirectional visibility lint (#2931), and the explain
   posture-label alignment (#2949).

2. 15.0.0 had NO Console section at all, despite bundling the objectui 14.0
   major (13.2.0→14.0.0, ~73 commits — first release-page disclosure since
   much of it rode unversioned in the 14.8.0 pin): the ADR-0057 ChatDock
   consolidation (including its breaking cleanup #2475), the Gantt batch,
   lists/forms/auth/Studio/i18n enhancements, two security fixes
   (#2485/#2410), and the six early-14.1 commits the 15.0.0 pin picked up.

3. The 15.1.0 sections were over-compressed; every domain is now expanded to
   its full changeset detail, and the Console 14.1 section covers all eight
   areas of the 94-commit range instead of seven bullets.

465 → ~1000 lines; structure mirrors v14.mdx (per-minor annotations inside
one major page, per docs/releases-maintenance.md).

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

Author: os-zhuang