refactor: rename example/ to service/

[sbalabanov]

Summary

The example/ tree holds the runnable server/client wiring for every domain — it is the composition root (knows the full queue topology, picks concrete extension impls, owns per-queue routing), not throwaway demo code. This renames it to service/ to reflect that role.

Changes

• git mv example/ → service/ (history preserved).
• Updated every reference to the path: Bazel labels (//example/...), Go importpaths (.../example/...), Makefile compose vars + build-*-linux/run-client-* targets, docker-compose.yml build contexts, integration/e2e suite composeFile paths and their BUILD data entries, and docs (CLAUDE.md, README.md, doc/, submitqueue/orchestrator/controller/dlq/README.md).
• Scoped replacements to actual path/label/importpath patterns — prose like "for example" and example.com fixtures were left untouched.

Documentation

• Rewrote service/README.md for the current layout: adds the runway service (was missing) and corrects stovepipe from "Ping-only" to its real Ping + Ingest + process-consumer shape; services table with ports/RPCs/stores.
• Added service/runway/README.md and service/stovepipe/README.md.
• Retitled service/submitqueue/README.md heading.

Validation

• make test — 65/65 pass
• bazel build //service/... (16 targets) and //test/... (12 targets) pass
• make gazelle clean (alphabetical reorder of one data list); gofmt clean

🤖 Generated with Claude Code

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