tools/local-dev: legacy-report-to-json CLI for synthetic UI testing

A Go module under tools/local-dev/legacy-report that converts the
"dg" / "gplus" engine .REP files in tools/local-dev/reports/ into the
JSON shape of pkg/model/report.Report. The output drives a DEV-only
synthetic-mode loader on the UI lobby so the map, inspectors, and
order-overlay can be exercised against rich game states without
playing many turns end-to-end.

Scope is intentionally narrow: only the fields the UI client decodes
today (planets, players, own ship classes, header). Importing
pkg/model/report keeps the parser and the typed contract in lockstep
— any backwards-incompatible schema change breaks the tool's
compilation before it ships. The README spells out the parity rule
for extending the parser alongside future UI decoders.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

tools/local-dev/legacy-report/go.sum

@@ -0,0 +1,2 @@
+github.com/google/uuid v1.6.0 h1:NIvaJDMOsjHA8n1jAhLSgzrAzy1Hgr+hNrb57e+94F0=
+github.com/google/uuid v1.6.0/go.mod h1:TIyPZe4MgqvfeYDBFedMoGGpEw/LqOeaOT+nhxU+yHo=