feat(web): Unified Insights dashboard — replaces the Overview/Cost/Pipeline apps

[hoangsnowy]

Change description

The desktop had three overlapping "what did the agents do" surfaces — an Overview KPI page, a standalone admin Cost page, and an "Agents" (PipelineStudio) window that ran a story through the 5 agents, i.e. a second run surface next to the Workflow app (which already runs the same agents as a graph). That redundancy read as confusing UX.

This folds all three into one observability dashboard, Insights (the pinned landing app), and makes Workflow the single run surface.

Insights (src/AgentOs.Web/Components/Pages/InsightsApp.razor):

• Headline KPIs: pipeline runs, success rate, avg QA rounds, LLM cost (billed) with the ≈ $X API would-be estimate carried over from PipelineStudio's status bar — so the $0 dev-runner path still shows a meaningful metered-API cost of the tokens.
• Four token-styled bar charts (no chart lib, no SVG — pure <div>s, all var(--…)): runs over time, per-agent calls + cost, spend by model (≈ API), avg latency per agent + QA-round distribution.
• The budget cap/enforce control (moved from the deleted Cost app), admin-gated.

Removed: PipelineStudio / OverviewApp / CostApp + their AppCatalog entries + the Settings "Cost" tab. Pinned apps 7 → 6 (Insights · Workflow · Board · Settings · Terminal · Files). Board's ticket "Open in Pipeline" action repoints to Workflow.

Data: reuse GetCostSummaryForTenantAsync; add a sibling GetInsightsExtraForTenantAsync (avg-latency-by-agent, QA-iteration distribution, runs-per-day) with the same Dapper fast-path + EF fallback + no-op-repo shape. No schema change — LatencyMs/Iteration columns already exist and are indexed.

Also folds in the one open CodeQL alert (cs/simplifiable-boolean-expression) and a README app-gallery refresh.

Type of change

• New feature (new agent / endpoint / capability)
• Refactor (no behavior change) — removes redundant run surface
• Documentation / README

Related issues

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Checklist

• dotnet build passes locally in Release mode (0 warnings, TreatWarningsAsErrors)
• dotnet test passes — 847 unit tests, 0 failures
• No secrets committed
• README updated (app gallery)
• Measurable results provided — see test plan

Test plan

• Build: dotnet build AgentOs.slnx -c Release → clean, 0 warnings.
• Unit: dotnet test AgentOs.slnx -c Release → 847 passed / 0 failed (28 E2E gated-skipped).
• E2E (full Aspire stack + seeded runs): opened Insights on the running desktop after seeding 12 runs / 75 per-agent metrics for default across 6 days. Verified live:
  • KPIs: 12 pipeline runs · 75% success · 1.8 avg QA rounds · $0.0000 billed / ≈ $0.6662 API.
  • Charts render with data: runs-over-time bars (04/08–10/08) and by-agent bars (Coding 21, Qa 21, Testing 21, Requirement 12 — matches the seed).
  • Recent runs table lists the seeded runs (Complete / Iteration-limit, QA rounds 1–3, dated).
  • Range selector (7d/30d/All) + budget cap panel + ≈ API sub-line all functional; no phantom-CSS, no circuit crash.
  • Dock shows the 6 pinned apps, Insights as landing; the removed "Agents" run window is gone.
• E2E test updates: LoginAndDesktopTests + WindowLifecycleTests (Overview→Insights, drop "Agents"); BudgetGateRealAuthTests repointed Settings→Cost tab → the Insights budget panel.

Note: promo screenshots (app-overview.png/app-pipeline.png/app-cost.png) were dropped from the README gallery; an app-insights.png capture via the Playwright recipe is a follow-up.