feat(enrichment tables): add network CIDR field to lookup results

[naa0yama]

Summary

Add a network field (CIDR notation) to GeoIP enrichment table lookup results.

The MaxMind MMDB lookup API (LookupResult) holds the network (CIDR) information for a given IP address, but the previous implementation only called decode() and discarded it. This PR adds the network field to all supported database types, bringing the output closer to parity with Elasticsearch's GeoIP processor.

Database type	Example output
City (GeoIP2-City / GeoLite2-City)	2.125.160.216/29
ISP (GeoIP2-ISP)	208.192.0.0/10
ASN (GeoLite2-ASN)	2600:7000::/24
Connection-Type (GeoIP2-Connection-Type)	201.243.200.0/24
Anonymous-IP (GeoIP2-Anonymous-IP)	101.99.92.179/32

Vector configuration

[enrichment_tables.geoip]
type = "geoip"
path = "/path/to/GeoLite2-City.mmdb"

[sources.demo]
type = "demo_logs"
format = "json"

[transforms.enrich]
type = "remap"
inputs = ["demo"]
source = '''
  .geoip = get_enrichment_table_record("geoip", {"ip": .ip })
  # .geoip.network now contains the CIDR, e.g. "2.125.160.216/29"
'''

[sinks.console]
type = "console"
inputs = ["enrich"]
encoding.codec = "json"

How did you test this PR?

• cargo test -p vector --lib enrichment_tables::geoip — 12/12 passed
• cargo test -p vector --lib enrichment_tables::mmdb — 5/5 passed (no impact)
• cargo clippy — no warnings
• cargo fmt --check — no formatting diff in changed code

Change Type

• Bug fix
• New feature
• Non-functional (chore, refactoring, docs)
• Performance

Is this a breaking change?

• Yes
• No

Does this PR include user facing changes?

• Yes. Please add a changelog fragment based on our guidelines.
• No. A maintainer will apply the no-changelog label to this PR.

References

• Closes: Enhanced CIDR enrichment with GeoIP and mmdb #24411
• Related: enhancement(enrichment_tables): Changes to support GeoIP Anonymous IP database #20946

Notes

• No new crate dependencies are required (ipnetwork is a transitive dependency of maxminddb; only to_string() is used).
• The Anonymous-IP database field documentation was missing since enhancement(enrichment_tables): Changes to support GeoIP Anonymous IP database #20946, so it is included in this PR as well.
• Please read our Vector contributor resources.

---

A note from the author: This is my first contribution to a Rust project. I am a non-native English speaker and have been writing this PR with the help of translation tools, so I would appreciate it if reviewers could keep comments concise and straightforward. Thank you for your patience and understanding!

[github-actions]

All contributors have signed the CLA ✍️ ✅
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[naa0yama]

I have read the CLA Document and I hereby sign the CLA

[naa0yama]

Hello,
How's the review of this PR going?

I've completed the necessary information and code fixes, so please check it out.

[naa0yama]

@domalessi @pront

Hello,
How is the PR progressing? I'm looking forward to it being included in the release.

[pront]

@codex review

[chatgpt-codex-connector]

Codex Review: Didn't find any major issues. More of your lovely PRs please.

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[pront]

Thank you. Looks good. Please address the merge conflicts.

[naa0yama]

@pront

Thank you for your reply.
I've tried to resolve the conflict. Please check it.