geoprobe: E2E test in Dockernet

[nikw9944]

RFC Reference: rfc16-geolocation-verification.md — Phase 1, item 4 (Deployment)
Tracking issue: #2893

Goal

Validate the full DZD → Probe → Target chain end-to-end in Dockernet.

Scope

• New test file following existing patterns in e2e/device_telemetry_test.go (uses testcontainers-go, devnet.New(), require.Eventually())
• Spin up: 1 DZD device + 1 geoProbe server + 1 target listener in Docker
• Configure via CLI flags (no onchain setup needed):
  • Telemetry agent: --additional-child-probes=<probe-addr>
  • geoProbe: --additional-parents=<dzd-pubkey>:<dzd-addr>, --additional-targets=<target-ip>
• Verify: DZD sends TWAMP + Offset to probe → probe caches offset, measures target, sends composite offset → target receives and verifies signature chain
• Assert: target logs show valid signature chain and plausible RTT values
• Add Dockerfile for geoprobe-agent and geoprobe-target (or build inline as existing tests do)

Files to change/create

• e2e/geolocation_test.go — new E2E test file
• e2e/internal/devnet/ — extend DeviceSpec or add ProbeSpec for geoProbe container support
• Dockerfiles for new binaries (if needed beyond existing Go build patterns)

Estimated scope

Medium–Large (~400–600 lines)

Dependencies

Depends on #2899, #2900, and #2901.

[ben-dz]

The telemetry <-> probe part is already done. I'm currently doing the probe <-> target part, but using --additional-targets until we get the onchain users & targets working.