feat(invoices): M7 dashboard widget + tests + plan status

Adds the missing bits that turn M1–M6 into a coherent shippable
product rather than a pile of commits.

Dashboard widget (M7)
- InvoicesOpenWidget.svelte: open + overdue totals in the primary
  currency, top-3 oldest overdue with "X Tage überfällig" under each,
  empty-state CTA for first-time users
- Registered as `invoices-open` in WIDGET_REGISTRY and the component
  map. Default size medium, no requiredBackend (local-first, no API)
- Fixed pre-existing test gap: validBackends list was missing 'body'
  (body-stats widget has been failing silently) — added so the check
  protects against drift for real

Tests (45 total, all green)
- totals.test.ts (9): computeLineTotal with discount+vat, grouping
  invariant (breakdown sums == invoice totals), rounding edges
- pdf/qr-bill.test.ts (17): generateSCORReference stability +
  spec-validity via swissqrbill's own isSCORReferenceValid, buildQRBillData
  eligibility gates (currency, IBAN, address, amount), CH + DE address
  parser paths, referenceNumber-preferred-over-regen invariant
- mail-template.test.ts (12): subject/body composition (with/without
  subject, CHF vs EUR QR-hint, empty recipient fallback), mailto
  spaces-as-%20 patch, looksLikeEmail edge cases

Plan (docs/plans/invoices-module.md)
- Updated with commit SHAs per milestone, testing status, and the
  explicit list of open items (Logo-Upload, AI-Tools, sync collision,
  structured addresses, finance cross-link, camt bankabgleich) so the
  next coder knows exactly what's parked where

Unresolved: browser smoke test couldn't run — SSR is broken for all
module routes in the current tree (pre-existing, likely from the
parallel Spaces refactor; /library, /todo, /contacts all return 500
the same way). Unit tests + clean bundle build (M4) + type-check are
the coverage we have.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

docs/plans/invoices-module.md

@@ -2,9 +2,29 @@
 
 ## Status (2026-04-20)
 
-**M0 Planning** — dieser Plan. Noch kein Code.
+**M1–M7 DONE** — solo-tauglich, ohne Logo-Upload + AI-Tools.
 
-Nächster Schritt: M1 Skelett (Modul registriert, Dexie-Table, Guest-Seed, leere ListView).
+| Milestone | Commit | Notes |
+|---|---|---|
+| M1 Skelett | `2cf89ce26` | Modul registriert, Dexie v27, Encryption-Registry, leere ListView |
+| M2 CRUD | `8d00ee069` | Store, Totals, Status-Maschine, ListView mit Stats-Cards, Routes |
+| M3 Settings | in M2 | SenderProfileForm fertig, **Logo-Upload offen** (uload-Integration nötig) |
+| M4 PDF Basic | `2dc298a79` | pdf-lib, pagination, preview + download |
+| M5 QR-Rechnung | `5af23d30b` | swissqrbill/svg + PNG-Overlay, SCOR auto, address-parser-Heuristik |
+| M6 Versand | `08b7ac16b` | SendModal mit mailto + PDF-Download + Confirm → status sent |
+| M7 Dashboard | pending commit | InvoicesOpenWidget mit Offen/Überfällig + Top-3 älteste überfällig |
+
+**Tests (45+ green):** totals math, SCOR + address-parser (swissqrbill `isSCORReferenceValid` roundtrip), mail template + mailto encoding.
+
+**Offene Arbeit vor "produktiv einsetzbar":**
+- **M3-Polish:** Logo-Upload via uload → erscheint im PDF-Header
+- **M8 AI-Tools:** `create_invoice` (propose), `mark_paid` (propose), `list_invoices` (auto), `get_invoice_stats` (auto) — braucht Planner-Drift-Guard-Update
+- **Nummernkreis-Multi-Device-Kollision:** dokumentiert als gap (pragmatisch, solo-MVP-tauglich)
+- **Strukturierte Adressen:** Heuristik-Parser deckt Standard-CH/DE ab; komplexere Adressen fehlen → User sieht in Warning, was fehlt
+- **Bezahlte Rechnung → finance-Transaktion:** Cross-Modul-Hook, Phase 3
+- **camt.053 Bankabgleich:** Phase 2
+
+Nächster Schritt: M3 Logo-Upload ODER M8 AI-Tools ODER Real-World-Dogfooding (erste eigene Rechnung an einen echten Kunden).
 
 ---