docs(contributing): adopt the org Wave issue template

[abrcrmb]

What and why

Adopt Kinlock's single issue format in this repo so Wave and other external contributors get scope,
evidence and a completion test they can work from, and so the roadmap rows the seeded backlog maps to
exist here before anyone claims an issue.

Changes

• .github/ISSUE_TEMPLATE/wave-task.md replaced with the org template from Kinlock-Org/.github
  PR docs: link the live testnet app; add README badges #26: Task, Context, mandatory context review, Why we need this, Scope (including the
  do-not-touch list), Suggested implementation, Done means, Tests, Documentation, Verify commands,
  PR rules, Tier, Related roadmap rows, Questions.
• Seven TODO rows added so this copy stays identical to canonical and to the other repo copies:
  M1-38, M1-39, M1-40, M1-41, M2-20, M2-21, M3-27.
• Changelog entry and Last updated; §3 progress counts recomputed with roadmap-progress.
• Wave issues opened in this repo and the rows they map to: Mixed schema_version: replay fixtures and handler tests for every event version #34 → M2-14, Document the list API as a checked reference: docs/API.md plus a route-parity test #35 → M2-20, Pin the amount precision boundary: what toBaseUnits refuses at the i128 and NUMERIC(39,0) limits #36 → M2-21, Verify the README on a clean machine, then fix the counts and commands that are wrong #37 → W-04.

Hard rules / invariants touched

None changed. The review block exists to make §1 (docs outrank initiative), §2 (ask-first list),
§3 (hard rules) and §4 (deferred list) legible to someone who has not read them.

Tests

Docs, template and roadmap rows only — no code changed, so no build or test suite in this repo is
affected and none was run. Commands actually run, real output:

duplicate row IDs in ROADMAP.md: 0 (must be 0)
M1-38 identical to canonical
M1-39 identical to canonical
M1-40 identical to canonical
M1-41 identical to canonical
M2-20 identical to canonical
M2-21 identical to canonical
M3-27 identical to canonical
new rows present: 7 of 7
template byte-identical to the org template
remaining diff lines vs canonical ROADMAP.md: 10 (expected: Last updated, the four §3 progress rows, W-05, Changelog)

Docs / ADR

Template and ROADMAP.md. No behaviour, API, event or constant change, so no ADR. The issue-format
reference itself lives in Kinlock-Org/.github docs/wave-issue-format.md (PR #26).

Roadmap

Rows added, all TODO: M2-20, M2-21 (owned here) plus M1-38, M1-39, M1-40, M1-41, M3-27 mirrored so all five copies match. No row moved to DONE; W-04 and W-05 are org-owned and change elsewhere.

Changelog entry added: yes. Last updated and the §3 counts refreshed.

Assumptions and open questions

• The seven rows are inserted byte-identically into all five ROADMAP.md copies (this one,
  Kinlock-Org/.github/docs/ROADMAP.md and the three sibling repos) so scripts/roadmap-merge sees
  no divergence for them. Changelog lines differ per repo by design and union at the next merge.
• W-05 is an org row and is deliberately left TODO here — §12 says a cross-cutting row
  changes only in the PR that completes it (.github docs: link the live testnet app; add README badges #26). roadmap-merge will take canonical's
  side, the same way it took canonical's F-11 in the reconcile run.
• Cross-cutting rows (F-18, F-19, W-04, W-05) are not re-statused here for the same reason.
• If you would move a tier before the cycle opens, say so on the issue: tier drives Wave points.