feat(node-ui): add shared context graph empty states

[Jurij89]

Summary

• Adds shared Context Graph EmptyState and StatStrip primitives for S9, with layer-aware tone support and reusable styling.
• Replaces ad hoc empty/status panels and stats across Overview, layer views, graph/loading states, documents, VM hero, activity feed, query, assertions, and sub-graph overview where safe for this PR scope.
• Implements the M5 interim Shared Working Memory Assertions empty state without changing the backend list path, so real rows still render when listAssertions(cg, 'swm') returns data.

Related

• Follow-up to fix(node-ui): align context graph label fallbacks #611.
• Context Graph UX rollout PR 2.2: S9 + M5 from agent-docs/context-graph-implementation-plan.md section 7.3.
• Leaves G-BACKEND-M5 population behavior for a later backend-gated change.

Files changed

File	What
packages/node-ui/src/ui/views/project/primitives.tsx	Adds shared EmptyState, StatStrip, and layer tone helpers.
packages/node-ui/src/ui/views/project/components.tsx	Refits Context Graph empty states, status panels, stat rows, and SWM Assertions interim copy.
packages/node-ui/src/ui/components/ActivityFeed.tsx	Uses the shared empty-state pattern for empty activity feeds.
packages/node-ui/src/ui/styles.css	Adds shared empty/stat styling and removes old double-wrapper treatments where replaced.
packages/node-ui/test/context-graph-empty-stat-components.test.ts	Covers shared primitives and WM/SWM Assertions empty/list behavior.
packages/node-ui/test/context-graph-contrast.test.ts	Adds shared empty/stat text selectors to contrast coverage.
packages/node-ui/test/vm-hero-banner.test.ts	Updates VM hero stat assertions for the shared StatStrip.

Test plan

• pnpm --filter @origintrail-official/dkg-node-ui exec vitest run test/context-graph-empty-stat-components.test.ts test/vm-hero-banner.test.ts test/layer-graph-panel.test.ts test/context-graph-contrast.test.ts test/use-memory-entities-counts.test.ts test/ka-detail-label.test.ts test/project-view-navigation.test.ts test/ui-compat.test.ts
• pnpm --filter @origintrail-official/dkg-node-ui run build
• pnpm --filter @origintrail-official/dkg-node-ui run build:ui
• git diff --check
• Playwright smoke against http://127.0.0.1:5178/ui/: Context Graph Overview showed the shared StatStrip, empty activity used shared EmptyState, and Shared Memory > Assertions showed the M5 interim empty state.
• Local PR review from pr-diff.patch: round 1 found two styling fidelity issues; round 2 returned {"comments":[]}.

Note: the local dev node emitted repeated API 500 console errors during browser smoke due its local data/API state. The UI still booted and the PR-specific Context Graph states rendered; this is not caused by this UI-only change.

[github-actions]

Codex review completed — no issues found.

[github-actions]

🟡 Issue: This VM-specific override now has the same specificity as the shared .v10-empty-state / .v10-stat-strip rules that are declared later, so those later rules win for overlapping properties. In practice the Verified Memory hero falls back to the generic empty-state spacing/surface, and the new StatStrip container also loses the intended v10-vm-hero-stats sizing. Move the VM overrides below the shared primitive block or increase specificity (for example .v10-vm-hero .v10-empty-state.v10-vm-empty-state and .v10-stat-strip.v10-vm-hero-stats).