fix(pr-to-green): distinguish underived queue issue numbers

[thewrz]

This was written agentically; verify its assertions:

Why

Forge-derived queues reported issue #0 even though they had never derived issue linkage, making unknown data look like a broken link.

What

Emit JSON null and records issue=null for underived issue numbers, rendering them as a dash in tables. Preserve real plan issue numbers and document the column semantics.

Decisions

Use the issue's preferred unknown-value representation without adding API calls. The merge gate already checks PR/head/base rather than issue linkage; integration regressions verify unknown linkage passes and genuine base mismatches fail. Condense adjacent prose to satisfy the existing skill-size limit.
base=origin/main
files=4
total.insertions=58
total.deletions=25
total.lines=83
operational.files=4
operational.insertions=58
operational.deletions=25
operational.lines=83
generated.files=0
generated.insertions=0
generated.deletions=0
generated.lines=0
lockfile.files=0
lockfile.insertions=0
lockfile.deletions=0
lockfile.lines=0
fixture.files=0
fixture.insertions=0
fixture.deletions=0
fixture.lines=0
non_operational.files=0
non_operational.insertions=0
non_operational.deletions=0
non_operational.lines=0

Testing

• Regression red: eight expected assertion failures before implementation.
• agent-run.sh --cmd test --only pr-queue,pr-to-green-merge-gate: 218 assertions passed.
• agent-run.sh --cmd test: 107 suites, shellcheck and repository checks passed (ALL GREEN).

🤖 Co-authored by Codex GPT-6 Astra.

Closes #601

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[thewrz]

This was written agentically; verify its assertions:

Adversarial review receipt

• Reviewer: provider=anthropic; model=claude-fable-5-1; effort=high; mode=cross-provider (reason: Explicit invocation override; Fable 5.1 high)
• Counts: P1=0; P2=0; total=0
• Reviewed head: 4e5251e
• Diff payload: wrzonance/agent-kit:604:285e07f0f38ceec7564c28c83f3594592a19e9666ea00a0601066319144e3140
• Confirmed finding: none confirmed

🤖 Co-authored by Codex GPT-6.

[thewrz]

This was written agentically; verify its assertions:

Review ledger

Machine-readable record of every review already performed on this PR.

{
  "version": 1,
  "pr": 604,
  "repo": "wrzonance/agent-kit",
  "reviews": [
    {
      "kind": "adversarial",
      "provider": "anthropic",
      "model": "claude-fable-5-1",
      "effort": "high",
      "mode": "cross-provider",
      "harness": "codex",
      "head_sha": "4e5251e78d3a5010abe0a18e40da3ad1583f1222",
      "covered_heads": [
        "4e5251e78d3a5010abe0a18e40da3ad1583f1222"
      ],
      "diff_payload": "wrzonance/agent-kit:604:285e07f0f38ceec7564c28c83f3594592a19e9666ea00a0601066319144e3140",
      "counts": {
        "p1": 0,
        "p2": 0
      },
      "reviewed_at": "2026-09-05T05:29:05Z"
    }
  ]
}

🤖 Co-authored by Codex GPT-6.