feat(intake): structured per-service intake questions

Services declare up to 8 intake fields (text/yesno, required) stored
as JSONB; shared/intake.go is the single normalization point — slug
keys, label/dup/unknown-key rules, yes/no canonicalization. Booking
create validates answers against the service declaration (missing
required -> 400), unknown keys are dropped before persist.

Answers surface on UpcomingBooking and CustomerBookingView; the
services page gains a compact editor and the public form renders
declared questions under contact details. Verified live end-to-end.

Generated with [Devin](https://devin.ai)

Co-Authored-By: Devin <158243242+devin-ai-integration[bot]@users.noreply.github.com>

apps/backend/internal/api/server.go

@@ -379,6 +379,7 @@ func NewServer(cfg config.Config, pools *db.Pools) (*Server, error) {
 			CustomerEmail  string  `json:"customerEmail" binding:"required,email"`
 			CustomerPhone  string  `json:"customerPhone"`
 			Notes          string  `json:"notes"`
+			Intake         map[string]string `json:"intake,omitempty"`
 			StartsAt       string  `json:"startsAt" binding:"required"`
 			EndsAt         string  `json:"endsAt" binding:"required"`
 		}