feat(service-integrations): phase 2 — integration widget & app form UI

- Add 6 renderer components: StatCard, Gauge, List, Progress, AlertBanner, Chart
- Add IntegrationWidget container with auto-refresh, loading, error states
- Add IntegrationAlertOverlay for layout-level critical alerts
- Add IntegrationConfigFields for dynamic form generation from Zod schemas
- Register integration type in WidgetRenderer
- Extend WidgetCreationForm with integration app/endpoint pickers
- Extend AppForm with integration config section and test connection button
- Add /api/integrations/alerts endpoint

plans/service-integrations/phase-5-portainer.md

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+# Phase 5: Portainer Integration
+
+**Status:** ⬜ Not Started
+**Parent plan:** [PLAN.md](./PLAN.md)
+**Domain:** backend
+
+## Objective
+Implement Portainer integration to display container and stack status from Docker environments managed by Portainer.
+
+## Tasks
+
+- [ ] Task 1: Create `src/lib/server/integrations/portainer/schema.ts` — Zod schemas for auth config (`{ apiKey: string, endpointId: number }`) and endpoint responses.
+- [ ] Task 2: Create `src/lib/server/integrations/portainer/client.ts` — HTTP client for Portainer API. Auth via `X-API-Key` header. Endpoints: `/api/endpoints/{id}/docker/containers/json`, `/api/stacks`, `/api/endpoints/{id}/docker/containers/{cid}/json`.
+- [ ] Task 3: Create `src/lib/server/integrations/portainer/transform.ts` — Transform: containers → summary (running/stopped/error counts as stat-card), container list with state + CPU/memory, stacks → list with up/down status.
+- [ ] Task 4: Create `src/lib/server/integrations/portainer/index.ts` — Integration implementation. Endpoints: `container-summary` (stat-card), `container-list` (list), `stack-status` (list). testConnection: fetch endpoints list.
+- [ ] Task 5: Register Portainer integration in registry.
+
+## Files to Modify/Create
+- `src/lib/server/integrations/portainer/schema.ts` — new
+- `src/lib/server/integrations/portainer/client.ts` — new
+- `src/lib/server/integrations/portainer/transform.ts` — new
+- `src/lib/server/integrations/portainer/index.ts` — new
+- `src/lib/server/integrations/registry.ts` — modify: register Portainer
+
+## Acceptance Criteria
+- Container summary shows running/stopped/error counts
+- Container list shows name, state, image, CPU/memory usage
+- Stack status shows stack names with up/down indicators
+- Test connection validates API key and endpoint ID
+- Handles multiple Portainer endpoints
+
+## Notes
+- Portainer API uses API key in `X-API-Key` header
+- Container stats (CPU/memory) require a separate API call per container — limit to top N for performance
+- Stack status comes from a separate endpoint
+- endpointId is required — Portainer manages multiple Docker hosts
+
+## Review Checklist
+- [ ] All tasks completed
+- [ ] Performance: limited container stats calls
+- [ ] Code follows project conventions
+
+## Handoff to Next Phase
+<!-- Filled in after completion -->