fix: restore embedded edit actions and persona fallback

[EterUltimate]

Summary

• restore embedded dashboard edit flows for jargon, expression/style reviews, and persona items
• make embedded toasts single, dismissible, and auto-clearing so stale notices no longer stick in the top-right corner
• treat blank/default persona config as "follow AstrBot current persona" and throttle missing-persona warnings
• add embedded static regression coverage and persona fallback tests

Issue

Fixes #182

Validation

• python -m pytest tests\unit\test_persona_selection.py tests\unit\test_persona_service.py tests\unit\test_persona_review_service.py -q
• python -m pytest tests\integration\test_webui_static_assets.py tests\integration\test_package_imports.py -q
• python -m py_compile config.py utils\persona_selection.py core\page_api.py
• node --check pages\dashboard\app.js
• git diff --check

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