Preserve tester states on migrated known issues and default new issues to state/new

Testers need legacy state/* labels carried from archived prk/issues onto their corresponding canonical known issues, and newly created canonical developer issues to start with state/new. Preserve exact existing vocabulary (new, unrefined, verified, fixed, cant-reproduce, duplicate, wontfix), avoid changing issue open/closed status or publication, never overwrite a tester-selected target state, and never transfer a duplicate source's state onto another issue's canonical target. Default state belongs to creation only so retries/retriage do not reset staff progress. Inspect/backfill canonical ownership through trusted markers and source import mapping, retain an audit of mutations, and validate counts and behavior. Production backfill complete and independently re-read through authenticated Forgejo API: 570 owned canonical issues updated; 10 nonlegacy known issues untouched; existing labels and open/closed status preserved. State totals: new 184, verified 291, unrefined 65, fixed 21, cant-reproduce 7, wontfix 1, duplicate 1. Private additive-maintenance audit and script retained under /home/mathias/.local/state/prk/legacy-tester-states-20261026.json and backfill-legacy-tester-states.py. Creation-only state/new implementation is committed as 3317ea2f1 and pushed on feature/preserve-known-issue-states in PRK.Reporting, with regression tests and README. Pull request #2870: https://git.project-rk.com/prk/engines/pulls/2870 (base develop). Red-green regression reproduced (4 failing before change); isolated reporting harness passed 121 tests, 2 SQL tests skipped; standalone coordinator Release build succeeded with 0 warnings/errors via .NET SDK Docker. Full solution and SQL tests not run. Patch review found no verified findings but was partial due unrelated untracked Avalonia artifacts, which remain untouched. Remaining blocker: merge/release coordinator change, then production verification of creation-time state/new; automatic default is not yet deployed. User authorized committing and opening the coordinator PR; unrelated untracked Avalonia artifacts were left untouched.