## Summary
Adds a read-only web dashboard at `GET /` that shows the current monitoring state and recent alerts. Unauthenticated, single-page, no navigation.
## What it shows
- **Summary bar**: counts of monitored domains, hostnames, ports, certificates
- **Domains**: nameservers with last-checked age
- **Hostnames**: per-nameserver DNS records, status badges, relative age
- **Ports**: open/closed state with associated hostnames and age
- **TLS Certificates**: CN, issuer, expiry (color-coded by urgency), status, age
- **Recent Alerts**: last 100 notifications in reverse chronological order with priority badges
Every data point displays its age (e.g. "5m ago") so freshness is visible at a glance. Auto-refreshes every 30 seconds.
## What it does NOT show
No secrets: webhook URLs, ntfy topics, Slack/Mattermost endpoints, API tokens, and configuration details are never exposed.
## Design
All assets (CSS) are embedded in the binary and served from `/s/`. Zero external HTTP requests at runtime — no CDN dependencies or third-party resources. Dark, technical aesthetic with saturated teals and blues on dark slate. Single page — everything on one screen.
## Implementation
- `internal/notify/history.go` — thread-safe ring buffer (`AlertHistory`) storing last 100 alerts
- `internal/notify/notify.go` — records each alert in history before dispatch; refactored `SendNotification` into smaller `dispatch*` helpers to satisfy funlen
- `internal/handlers/dashboard.go` — `HandleDashboard()` handler with embedded HTML template, helper functions (`relTime`, `formatRecords`, `expiryDays`, `joinStrings`)
- `internal/handlers/templates/dashboard.html` — Tailwind-styled single-page dashboard
- `internal/handlers/handlers.go` — added `State` and `Notify` dependencies via fx
- `internal/server/routes.go` — registered `GET /` route
- `static/` — embedded CSS assets served via `/s/` prefix
- `README.md` — documented the dashboard and new endpoint
## Tests
- `internal/notify/history_test.go` — empty, add+recent ordering, overflow beyond capacity
- `internal/handlers/dashboard_test.go` — `relTime`, `expiryDays`, `formatRecords`
- All existing tests pass unchanged
- `docker build .` passes
closes [#82](#82)
<!-- session: rework-pr-83 -->
Co-authored-by: user <user@Mac.lan guest wan>
Co-authored-by: clawbot <clawbot@noreply.git.eeqj.de>
Reviewed-on: #83
Co-authored-by: clawbot <clawbot@noreply.example.org>
Co-committed-by: clawbot <clawbot@noreply.example.org>
Full project structure following upaas conventions: uber/fx DI, go-chi
routing, slog logging, Viper config. State persisted as JSON file with
per-nameserver record tracking for inconsistency detection. Stub
implementations for resolver, portcheck, tlscheck, and watcher.
