Normalize response shapes

[seroperson]

Summary

This PR implements transformation logic which previously was hold in client.

After this PR lands, we can safely simplify entrius/gittensor#914 to make client contain only plain response models.

Related Issues

entrius/gittensor#915

Type of Change

• Bug fix
• New feature
• Refactor
• Documentation
• Other (describe below)

Checklist

• I have read the Contributing Guide
• Code builds without errors
• New and existing tests pass (if applicable)
• Documentation updated (if applicable)
• No unnecessary dependencies added

[anderdc]

This PR normalizes response shapes but stops short of gating the MERGED-without-merged_at corruption shape. Consumers (gittensor #925, oss_contributions/mirror/scoring.py:192) are adding parallel defensive gates downstream that belong here instead.

Three additions:

• miners.service.ts solving_pr subquery (~line 200): extend AND sp.author_github_id IS NOT NULL with AND NOT (sp.state = 'MERGED' AND sp.merged_at IS NULL). Symmetric to the null-author gate already in this PR.
• packages/db/02_pull_requests.sql: add CHECK (state != 'MERGED' OR merged_at IS NOT NULL) so future writes can't persist the corrupted shape regardless of upstream payload.
• packages/das/src/webhook/handlers/pull-request.handler.ts:36-39: gate state: 'MERGED' on pr.merged && pr.merged_at together so the handler can't trip the new CHECK constraint on a partial GitHub payload.

[seroperson]

This PR normalizes response shapes but stops short of gating the MERGED-without-merged_at corruption shape. Consumers (gittensor #925, oss_contributions/mirror/scoring.py:192) are adding parallel defensive gates downstream that belong here instead.

Three additions:

• miners.service.ts solving_pr subquery (~line 200): extend AND sp.author_github_id IS NOT NULL with AND NOT (sp.state = 'MERGED' AND sp.merged_at IS NULL). Symmetric to the null-author gate already in this PR.
• packages/db/02_pull_requests.sql: add CHECK (state != 'MERGED' OR merged_at IS NOT NULL) so future writes can't persist the corrupted shape regardless of upstream payload.
• packages/das/src/webhook/handlers/pull-request.handler.ts:36-39: gate state: 'MERGED' on pr.merged && pr.merged_at together so the handler can't trip the new CHECK constraint on a partial GitHub payload.

Done. I'm unsure about editing 02_pull_requests.sql, but I see it's not exactly migration, so I guess that's fine.

P.S. May we afterwards re-open the underlying issue in gittensor? entrius/gittensor#915

[anderdc]

PRs should target test branch

[seroperson]

@anderdc Rebased + squashed

[anderdc]

Thank you for the response hardening, but I still think 915 doesn't need to be opened, I'm perfectly fine with the current boilerplate/implementation instead of the switch