docs: correct README license label MIT → GPL-3.0-or-later (#1744)

[Kpa-clawbot]

Fixes #1744

Summary

README's License section advertised MIT, but the repo's LICENSE file is GNU GPL v3 (GNU GENERAL PUBLIC LICENSE / Version 3, 29 June 2007). Updated the README label to the SPDX identifier GPL-3.0-or-later so it matches the actual license text.

Change

• README.md: MIT → GPL-3.0-or-later (single line)

TDD exemption

Pure docs change, no behavior. Per AGENTS.md TDD section: "Pure docs / pure comments: no test required. Kent Beck gate still runs, rubber-stamps with 'no behavior change' justification." No production code, no tests touched.

Out of scope

The reporter also flagged two other items; per triage these are explicitly out of scope here:

• Root-directory clutter — already tracked by chore: repo cleanup — archive stale top-level design docs, consolidate docs/ hierarchy, move root tests/ #1385.
• Missing "About" page — needs its own issue; not addressed in this PR.

[Kpa-clawbot]

Polish review — trivially safe docs (1-line README label)

3-axis status:

• git: MERGEABLE
• CI: UNSTABLE — 🎭 Playwright E2E Tests failing on test-issue-1630-reach-mobile-e2e.js (Error: no repeater with reach links found in fixture), identical failure on master since 2026-06-16. Not introduced by this PR (only README.md touched). Pre-existing flake → tracked separately; does not gate this change.
• review: 0 BLOCKER / 0 MAJOR / 0 NIT

Diff: README.md line 273 only — MIT → GPL-3.0-or-later. Matches LICENSE (GNU GPL v3, line 1-2: "GNU GENERAL PUBLIC LICENSE / Version 3, 29 June 2007"). SPDX identifier GPL-3.0-or-later is the correct form. Out-of-scope items (root-dir clutter, About page) correctly punted in PR body.

Kent Beck gate: Pure docs exemption (per AGENTS.md TDD section). No behavior change. Rubber-stamped.

Verdict: merge-ready on content & process. Cannot auto-merge under strict gate (UNSTABLE due to unrelated Playwright flake); operator can merge manually with gh pr merge 1746 --squash --admin or wait for the flake to be triaged.

[Kpa-clawbot]

🤖 Hourly PR-watch review

Verdict: APPROVE (CI blocked by #1747, not by this PR)

One-character correctness fix: MIT → GPL-3.0-or-later. Matches the actual LICENSE file. Closes #1744.

CI status

Playwright failing everywhere on the same pickRepeaterWithReach precondition since 2026-06-16 — see #1747 for the fixture-aging root cause + fix. Rebase after #1747 merges and this should flip to CLEAN.

TDD exemption

Pure docs (1-line README). No test required per AGENTS.md exempt rule.

Findings: 0 BLOCKER / 0 MAJOR / 0 MINOR

Reviewed by: orchestrator self-review (no surface complexity).