Add technical check history

A car's mandatory roadworthiness inspections — przegląd techniczny, MOT,
TÜV — had nowhere to live. Log them behind Service history, which this
mirrors minus the odometer: an inspection falls due on a date whatever
the mileage reads.

The cycle is legal rather than mechanical, and it is not constant — a new
car's first check falls due years later than its third. So the car's
technical_check_interval_days only prefills the next date, and any check
overrides it with the valid-until printed on its own certificate. A
failed check derives no next date at all: reading one off a failure would
stamp a reassuring "valid until" on a car that just flunked.

The next-due date and its status are derived on every read rather than
stored, for the same reason documents are — a stored verdict goes stale
as the date passes. The response carries the same expiry shape documents
use, so the web app reuses the existing badge rather than growing a
second one.

Each check records result, cost, station and notes, and holds the
certificate as its single attachment on the same terms as every other
record.

Needs `node scripts/setup-pocketbase.mjs` to create technical_checks and
add the interval to cars. The reformatting in records.go is gofmt
realigning the car struct around a longer field name.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

Web App/web/src/api.js

@@ -135,6 +135,16 @@ export const api = {
     request(`/service-records/${id}`, { method: "PATCH", body: JSON.stringify(body) }),
   deleteService: (id) => request(`/service-records/${id}`, { method: "DELETE" }),
 
+  // Technical checks — roadworthiness inspections. nextCheckDate and the expiry
+  // assessment are derived server-side from the certificate's valid-until date,
+  // falling back to the car's interval.
+  listCarTechnicalChecks: (carId) => request(`/cars/${carId}/technical-checks`),
+  createTechnicalCheck: (body) =>
+    request("/technical-checks", { method: "POST", body: JSON.stringify(body) }),
+  updateTechnicalCheck: (id, body) =>
+    request(`/technical-checks/${id}`, { method: "PATCH", body: JSON.stringify(body) }),
+  deleteTechnicalCheck: (id) => request(`/technical-checks/${id}`, { method: "DELETE" }),
+
   // Parts
   listCarParts: (carId) => request(`/cars/${carId}/parts`),
   createPart: (body) => request("/parts", { method: "POST", body: JSON.stringify(body) }),
@@ -170,6 +180,7 @@ export const api = {
   files: {
     documents: attachment("/car-documents"),
     services: attachment("/service-records"),
+    technical: attachment("/technical-checks"),
     maintenance: attachment("/maintenance"),
     fuel: attachment("/fuel-entries"),
     parts: attachment("/parts"),