remove skips or crashes when matching multiple packages

When a `BundlePatch` matches multiple packages via a selector, `harp` either does not behave as expected or crashes.

## skip

```sh
# 1. Build a 4-package bundle (sorted: aaa < bbb < ccc < zzz)
cat > input.json <<'EOF'
{
"app/aaa": {"k": "v1"},
"app/bbb": {"k": "v2"},
"app/ccc": {"k": "v3"},
"app/zzz": {"k": "v4"}
}
EOF
harp from jsonmap --in input.json > in.bundle

# 2. Patch spec: remove aaa and bbb (adjacent in sorted order)
cat > patch.yaml <<'EOF'
apiVersion: harp.elastic.co/v1
kind: BundlePatch
meta:
name: remove-adjacent
spec:
rules:
- selector:
matchPath:
regex: "^app/(aaa|bbb)$"
package:
remove: true
EOF

# 3. Apply and observe
harp bundle patch --in in.bundle --spec patch.yaml > out.bundle
harp bundle dump --in out.bundle --path-only
```

**Actual behavior behavior**
app/bbb ← silently survived
app/ccc
app/zzz

**Expected behavior**
app/ccc
app/zzz

## crach

```sh
# Using the same 3-package bundle where all packages match:
cat > in3.json <<'EOF'
{"app/one": {"k": "v1"}, "app/three": {"k": "v3"}, "app/two": {"k": "v2"}}
EOF
harp from jsonmap --in in3.json > in3.bundle

cat > remove-all.yaml <<'EOF'
apiVersion: harp.elastic.co/v1
kind: BundlePatch
meta:
name: remove-all
spec:
rules:
- selector:
matchPath:
regex: ".*"
package:
remove: true
EOF

harp bundle patch --in in3.bundle --spec remove-all.yaml > out3.bundle
```

---

Version:
`0.2.12 [main:2025-04-30T22:12:09Z] (Go: go1.23.8 linux/amd64, Flags: defaults, Date: 2025-04-30T22:28:01Z)`

Start by reproducing both cases with the provided `harp from jsonmap`, `harp bundle patch`, and `harp bundle dump` commands and the adjacent-match and match-all YAML specs. Trace bundle patch handling for selectors matching multiple packages; done means every matching package is removed without being skipped, and removing all packages no longer crashes.

Written by the indexing model from the issue text.