feat(web): refine console typography and overview layout

[RyanLee-Dev]

The console gave metrics, charts, and operational tables nearly identical visual weight, while wide navigation and fixed breakpoints crowded smaller windows. This change introduces a compact metric strip, a fleet inventory with on-demand details, and flat attention and project tables. Fleet previews prioritize offline and degraded nodes when the list exceeds four nodes; full node management remains available.

Shared styles now use locally bundled IBM Plex Sans, consistent line icons, smaller corner radii, clearer light/dark surfaces, and wrapping header actions. Successful zero-session reads show next-step guidance, while unavailable, partial, and stale observations retain their existing disclosures. English and Chinese copy and the owning design/product documents are updated. Administration API boundaries are unchanged.

Validation:

• Web TypeScript check and production build passed; the existing large-chunk warning remains.
• Focused Overview unit/render tests passed.
• 22 browser acceptance tests passed across readiness, access, resources, and diagnostics.
• OpenAgentCore name guard and diff whitespace checks passed.
• Manually checked light/dark themes, English/Chinese, desktop and 390px layouts, first-run empty states, resource/settings pages, and fleet details using local fixtures.
• Fresh independent reviews completed with no outstanding findings.

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