Document corpus refresh processed-item conventions

[chubes4]

Summary

• Adds generic corpus refresh processed-item key conventions for document, chunk, and embedding revision dedupe.
• Documents the corpus refresh source types, key shapes, and batch metadata counters.
• Surfaces selected and retried batch result counts through run metrics and covers the convention with smoke tests.

Closes #2489

Tests run

• php tests/corpus-refresh-conventions-smoke.php
• php tests/run-metrics-smoke.php
• php tests/processed-item-claims-smoke.php
• ./vendor/bin/phpcs inc/Core/Corpus/CorpusRefreshConventions.php inc/Core/RunMetrics.php tests/corpus-refresh-conventions-smoke.php tests/run-metrics-smoke.php

Remaining risks

• This PR defines generic conventions and metrics plumbing only; corpus consumers still need to adopt these keys in their own refresh jobs.
• No dependency on another issue or PR.

AI assistance

• AI assistance: Yes
• Tool(s): OpenCode (gpt-5.5)
• Used for: Drafted the implementation, documentation, smoke tests, self-review cleanup, and verification commands for Chris to review.

[homeboy-ci]

Homeboy Results — data-machine

Lint

✅ lint — passed

ℹ️ Full options: homeboy docs commands/lint
Deep dive: homeboy lint data-machine --changed-since 6745e42

Artifacts and drill-down

• CI results artifact: homeboy-ci-results-data-machine-lint-quality-Linux-node24 contains immediate command JSON for this action invocation.
• Observation artifact: homeboy-observations-data-machine-lint-quality-Linux-node24 contains exported Homeboy run history for deeper queries.
• Drill-down: download the observation artifact, then run homeboy runs import <dir>, homeboy runs list, and homeboy runs findings <run-id>.
• Artifacts are attached to the workflow run: https://github.com/Extra-Chill/data-machine/actions/runs/26920077793

Test

✅ test — passed

• 212 passed

ℹ️ Auto-fix lint issues: homeboy refactor data-machine --from lint --write
ℹ️ Collect coverage: homeboy test data-machine --coverage
ℹ️ Save test baseline: homeboy test data-machine --baseline
ℹ️ Pass args to test runner: homeboy test -- [args]
ℹ️ Full options: homeboy docs commands/test
Deep dive: homeboy test data-machine --changed-since 6745e42

Artifacts and drill-down

• CI results artifact: homeboy-ci-results-data-machine-test-quality-Linux-node24 contains immediate command JSON for this action invocation.
• Observation artifact: homeboy-observations-data-machine-test-quality-Linux-node24 contains exported Homeboy run history for deeper queries.
• Drill-down: download the observation artifact, then run homeboy runs import <dir>, homeboy runs list, and homeboy runs findings <run-id>.
• Artifacts are attached to the workflow run: https://github.com/Extra-Chill/data-machine/actions/runs/26920077793

Audit

✅ audit — passed

• audit — 4 finding(s)
• Total: 4 finding(s)

Deep dive: homeboy audit data-machine --changed-since 6745e42

Artifacts and drill-down

• CI results artifact: homeboy-ci-results-data-machine-audit-quality-Linux-node24 contains immediate command JSON for this action invocation.
• Observation artifact: homeboy-observations-data-machine-audit-quality-Linux-node24 contains exported Homeboy run history for deeper queries.
• Drill-down: download the observation artifact, then run homeboy runs import <dir>, homeboy runs list, and homeboy runs findings <run-id>.
• Artifacts are attached to the workflow run: https://github.com/Extra-Chill/data-machine/actions/runs/26920077793

Tooling versions

• Homeboy CLI: homeboy 0.220.1+26d94b5e
• Extension: wordpress from https://github.com/Extra-Chill/homeboy-extensions
• Extension revision: 1f9ab9d7
• Action: unknown@unknown