feat(kiro): add S3 collection and plugin APIs

[warren830]

Summary

• add Kiro chat/completion log parsing and extraction
• add AWS S3 and optional IAM Identity Center clients, including separate report/log bucket support
• discover accounts and year/month scopes directly from exported S3 layouts
• collect and extract report, chat, and completion files with bounded concurrency and deduplication
• add connection validation, scope browsing, blueprint preparation, API routes, plugin wiring, and table-info coverage
• include anonymized gzip fixtures for exported interaction-log variants

Delivery sequence

This builds on the merged foundation PR #9073. The existing q_dev plugin remains available in this step so current consumers keep working; later sequential changes add Kiro Config UI and migrate dashboards before q_dev is removed.

The independent attribution helper landed separately in #9074.

Validation

• make mock
• make swag
• go test ./plugins/kiro/... -count=1
• go vet ./plugins/kiro/...
• go build ./plugins/kiro/...
• plugin-mode build with go build -buildmode=plugin
• all-Go-plugin registration guard: 45 impl directories / 45 registered plugins
• sensitive-data scan: only placeholder account 111111111111, no emails, aliases, local paths, or internal docs

The full local schema-E2E package remains blocked by this machine's libgit2 1.3 versus git2go's required 1.5; GitHub CI runs that package in its supported environment.

Signed-off-by: warren warren.chen830@gmail.com

Stacked follow-ups

Merge this series in order. All PRs are ready for review, but merge them strictly in this order:

1. feat(kiro): add S3 collection and plugin APIs #9075 — collection and plugin APIs
2. feat(config-ui): add Kiro connection support #9076 — Config UI and Kiro E2E
3. feat(grafana): add core Kiro dashboards #9077 — core Kiro dashboards
4. feat(grafana): migrate Kiro engineering dashboards #9078 — engineering dashboards
5. chore: remove the q_dev plugin #9079 — final q_dev removal

Each downstream branch is cumulative so CI sees all dependencies. Its repeated diff automatically disappears as preceding PRs merge.