chore: fix build dependencies and frontend config

Migrate Docker SDK from github.com/docker/docker (+incompatible)
to github.com/moby/moby/client v0.3.0 + moby/moby/api v1.54.0
(proper Go modules). Adapt all container/image/network operations
to the new moby API (Filters, ContainerListOptions, PullResponse,
InspectResult, etc.). Add AsyncTriggerDeploy runDeploy method.

Fix SvelteKit build: disable prerender, set strict=false for SPA,
bump vite-plugin-svelte to v5 for vite 6 compat.

Add .dockerignore to exclude .git, node_modules, plans.

Dockerfile

@@ -15,9 +15,6 @@ RUN apk add --no-cache git ca-certificates
 
 WORKDIR /build
 COPY go.mod go.sum ./
-
-# The project requires Go 1.25 (transitive dep from Docker SDK -> otelhttp).
-# GOTOOLCHAIN=auto lets Go 1.24 download the required toolchain automatically.
 ENV GOTOOLCHAIN=auto
 RUN go mod download
 
@@ -25,7 +22,7 @@ COPY . .
 # Copy built frontend into the expected embed location.
 COPY --from=frontend-builder /build/web/build ./web/build
 
-RUN GOTOOLCHAIN=auto CGO_ENABLED=0 GOOS=linux go build -ldflags="-s -w" -o /docker-watcher ./cmd/server
+RUN CGO_ENABLED=0 GOOS=linux go build -ldflags="-s -w" -o /docker-watcher ./cmd/server
 
 # Stage 3: Minimal runtime image
 FROM alpine:3.19