KEDA deployer: default minReplicaCount prevents scale-to-zero

The KEDA deployer defaults `minReplicaCount` to `1`, which means functions never scale to zero — KEDA will only scale down to the configured minimum.

**Location:** `pkg/keda/deployer.go`

```go
minScale := int32(1)
```

This value is set on the HTTPScaledObject's `Replicas.Min`. For scale-to-zero to happen, `minReplicaCount` must be `0`.

**Current behavior:** Functions always keep at least 1 replica running, even with no traffic.

**Expected behavior:** Consider defaulting to `0` so functions can scale to zero when idle, which is one of KEDA's main features. Users who prefer to avoid cold-start latency can explicitly set `scale.min: 1` in their function config.

**Trade-off:** Changing the default to `0` enables scale-to-zero but introduces cold-start latency for the first request after idle. The KEDA HTTP add-on interceptor handles this by holding the request until a pod is ready, so requests aren't dropped — but latency increases.

Start in pkg/keda/deployer.go at the minScale default and trace how it is assigned to the HTTPScaledObject's Replicas.Min. Done means idle functions can scale to zero by default while users can still set scale.min: 1 explicitly.

Written by the indexing model from the issue text.