## Why

The architecture stream now has a repeatable local debug workspace and a manually verified API-backed browser walkthrough, but the walkthrough still depends on an operator remembering route checks, seed order, and forbidden-fragment scans. An automated browser acceptance suite is needed now so required first-party console flows stay real, API-backed, and safe as platform, run, platform_web, and plugin features keep evolving.

## What Changes

- Add an automated browser acceptance suite for the local debug/API-backed console path.
- Cover login and navigation across 首页、服务器管理、插件市场、用户管理、AI 提供商管理, plus server detail and core plugin/server operation surfaces.
- Require the suite to seed or reuse the documented local debug fixture before browser checks run.
- Require fallback/demo-only data rejection and visible forbidden-fragment scanning on every accepted route.
- Require concrete commands that can run the suite locally and in CI-like verification without relying on manual browser-only evidence.
- No breaking changes are expected; this change automates an existing verified workflow instead of changing product behavior.

## Capabilities

### New Capabilities
- `browser-acceptance-suite`: Defines automated browser acceptance coverage for the API-backed management console, local debug fixture prerequisites, required route assertions, plugin/server lifecycle proof, fallback rejection, forbidden-fragment scanning, and verification commands.

### Modified Capabilities
- None.

## Impact

- Affected roots: `platform_web/`, `scripts/`, documentation, and potentially shared local debug fixtures under `platform/`, `run/`, and `plugins/` only as needed to support deterministic acceptance setup.
- Expected implementation areas: browser acceptance test harness, local debug stack orchestration or reuse hooks, visible content assertions, forbidden-fragment scanner, route coverage fixtures, and task evidence.
- Validation impact: requires frontend typecheck/tests/build, automated browser acceptance command, local debug smoke prerequisites, `scripts/check-structure.sh`, and `openspec validate implement-browser-acceptance-suite --strict`.