Give health and capacity facts one home

[SaladDay]

What

Each health and capacity fact now has one home in Web:

• Nodes owns the node list, each node's capacity and limits, host CPU, memory and free disk with 1 h / 6 h / 24 h charts (moved from the Sandbox metrics node dialog), Add node and Edit node (moved from Settings → Sandbox and scheduling). The node page's Capacity adds Cleanup pending; Retained / limit gets a one-line help tip that says what Core enforces: "The most sandboxes this node holds at once: starting, running and suspended."
• Overview keeps its compact capacity summary. Core, E2B and node rows are plain buttons that open Core metrics, Sandbox metrics and the node's page on Nodes. The anchored popovers, ConsolePopover, ui/popover and their CSS are deleted.
• Sandbox metrics keeps hosted Runtime time series and activity. The node table, the node dialog and the lifecycle KPI strip are gone; node names in the Runtime table and dialog open that node's page on Nodes. The runtime meta now reads "8 of 12 active · 4 suspended · …", the table's word, instead of a bare total.
• Settings → Sandbox and scheduling keeps setup, resources, rollout, reset and Automatic suspension (idle seconds and read-only snapshot retention). The Sandbox nodes table and the node route parameter are removed, and the page reads only the deployment, not the node and allocation inventory (useSandboxDeploymentState). The header links to Nodes, and the first save continues to Nodes → Add node.
• Core metrics now leads with the operator's questions: slots, queued, queue wait p95, interrupted Turns, database latency p95, CPU and memory. Go heap, goroutines, the DB pool and process CPU/RSS charts sit in a collapsed Diagnostics section. The Nodes and daemons KPIs are dropped; connected daemons stay in the Execution meta.
• Cleanup: CSS rules no component uses are deleted (.numeric-warning, .metrics-node-status, .settings-table-action, .runtime-embed, .sandbox-actions, .sandbox-empty, .sandbox-network-settings, .sandbox-rollout-*), runtimeSnapshotWhere is folded into runtimeSnapshot, and the rounded.popover token is gone.
• Docs: apps/web/PRODUCT.md records the split. DESIGN.md, docs/getting-started/nodes.md, docs/configuration.md, docs/getting-started/install.md, docs/web/index.md, docs/web/console-api-usage.md and contracts/agents-api/sandbox-deployment.md were updated, with zh mirrors and refreshed source_hash.

Why

UX polish lane C covers the daily check ("is it healthy, is capacity OK") and adding or resizing a node:

• The node table appeared on four pages and the five suspension cards on two.
• "6 hosted Runtimes" was shown while all six were not running.
• Core metrics led with Go internals.

No Core field, route or setting is added. RouteParams.node and the Settings node editor had no other caller, so they are deleted.

Verification

Rebased onto main 5dbf400 (#697, #699), keeping #697's setting names and wording and #699's Needs attention section and session naming.

• pnpm --filter @oac/web typecheck
• vitest run on sandbox, metrics, overview, settings, system, sessions, lib and i18n: 275 passed.
• Playwright against the fixture: overview-readiness, monitoring, diagnostics, nodes, sandbox-lifecycle, unified-settings, sandbox-reset, sandbox-generation, sandbox-rollout-details, system, access, wording and public-url. 82 passed. sandbox-lifecycle asserts Settings → Sandbox reads no /core/v1/sandbox/nodes (fails with the old loading); monitoring opens a node from the Runtime table. The sandbox-generation draft test no longer exercises a Settings node-inventory retry, since Settings no longer reads it.
• make check-docs, make check-names, pnpm --dir website check-translations and pnpm --dir website build (dead-link check).
• Screenshots (zh and en, 1440 and 390) of Overview, Nodes, a node page, Sandbox metrics, Core metrics and Settings → Sandbox and scheduling.

Skipped

• Full make check and the other Playwright specs (focused checks only).
• No Go change, so no go test or go vet.
• Phone-width table and tab fixes come in a separate PR.