fix(research): support overlap pagination on older gh

[petalas]

Summary

 gh_json(["--paginate", "--slurp", ENDPOINT])
-gh api --paginate --slurp ENDPOINT
+gh api --paginate ENDPOINT --jq '@json'
+decode every compact JSON page before publishing the snapshot

Keep complete open-PR pagination on GitHub CLI releases without --slurp. Normalize the legacy argument inside gh_json, leaving its callers unchanged. This preserves merged PR #1623's path-index fetching and avoids a caller conflict.

Reject absent or malformed pages. Preserve the previous complete snapshot when any page fails. Split only LF separators so embedded Unicode line separators survive. Single-response GraphQL behavior and the cache schema are unchanged.

Retain Douglas Colkitt's helper and cache design. Cinna Davis's earlier report identified the unsupported flag. This patch adds the correction and reproducible regression coverage. The sampled complex-new-helper-inventory task changed scope to tooling; this supplies no new helper inventory or bound improvement.

Evidence

• Before: the new legacy-argument regression fails with unknown flag: --slurp. After: all seven focused regressions pass in standard and optimized modes.
• The controls cover later-page drafts, Unicode/newline bodies, empty repositories, missing and malformed output, failed refreshes, cache preservation, offline reuse and GraphQL errors.
• The two-file patch applies cleanly to main 51122344de9382e784c7f89953456d8cd55513ef, including Tooling: search open-PR overlap by changed file path in find_overlap (no new kappa) #1623. All 60 research-workflow tests pass on that combined tree with no skips. All 49 pass on this branch with no skips.
• A live refresh completed with 392 open PRs and 639 Discussion records, complete pagination and no warnings, at 2026-10-14T16:53:29Z.
• Baseline bindings, warning-enabled bytecode compilation and diff checks pass. The selected record and its source pins are unchanged.

python3.12 -X dev -W error -B -m unittest discover -s tests -p 'test_research_*.py'
python3.12 -I -O -B tests/test_research_overlap_pagination.py
python3.12 -B scripts/research_baseline.py

Merge Danger

Door: two-way

Blast Radius: coordination

Only paginated REST decoding and its tests change. No scientific evidence, selected frontier or cache format changes. Overlap reports remain search leads, not novelty certificates. No full mathematical cold replay or hosted-CI result is claimed.

[Mister-Meeseeks]

Batch review at 9c2fdd89e553751e40ef8011716a249e8385d284.

Merged to main, preserving the original contributor commits and package attribution.

Reviewed scope: REST pagination preserves the nested-page contract without gh --slurp, including Unicode line separators, later-page drafts, failed refreshes and cached coverage. Seven regression groups verify failure retains prior complete data. No mathematical claim.

The pinned scoped command passed; the batch ledger contains its command, input hashes, environment and log. This incorporates the research/tooling contribution and does not change the selected κ or discharge the inherited multiplication-theorem assumptions.

Batch review, attribution and evidence. Thank you for the contribution.