Complete dashboard and release hardening

[chai1any]

What changed

• rebuilt the private dashboard around the ArcXiv-derived editorial design system
• completed authenticated search, analysis, workspace, session, recap, and memory workflows
• added first-run onboarding, connection recovery, light/dark themes, responsive behavior, and accessibility coverage
• formalized live dashboard API and browser contracts
• added broad retrieval-quality and native cross-platform installer gates

Why

The dashboard previously lacked complete end-to-end workflows and used an older visual system. Release confidence also depended too heavily on static checks and a narrow retrieval fixture.

Impact

Users get a coherent local-first console with evidence-rich results and durable knowledge workflows. CI now exercises a real paired browser session, search-quality coverage, and Linux/macOS/Windows distribution paths without weakening existing CLI or MCP behavior.

Validation

• Rust formatting, strict Clippy, and 318 tests
• 8 Chromium UI scenarios with automated WCAG checks
• live authenticated Chromium evidence-to-memory workflow
• 14 Python contract tests and documentation checks
• semantic precision/recall 1.0
• 12/12 search-quality queries rank the intended file first with no fixture leakage
• dashboard latency and pinned Perseus acceptance gates
• native installer round trip