Rename to rpmroute

The router began as a port of FreeRouting and has grown its own engine
(negotiated congestion, tree nets, exact checks, axis escapes), and
'freeroute' was one letter from the project it no longer follows. The
package, module and command are now rpmroute; the freeroute command stays
as an alias, and the RPMROUTE / RPMROUTE_ORACLE_JAVA variables fall back
to the old FREEROUTE names. Version 2026.10.07. Routing is unchanged: a
PCBench board routes to a byte-identical session either way.

tests/route/test_tree_nets.py

@@ -5,11 +5,11 @@ from __future__ import annotations
 
 import pytest
 
-from freeroute.board import build_board
-from freeroute.dsn import parse_dsn
-from freeroute.route import exact_router
-from freeroute.route.grid_router import GridRouter, RouteResult
-from freeroute.route.pipeline import _rule_clearance_dsn, _rule_width_dsn
+from rpmroute.board import build_board
+from rpmroute.dsn import parse_dsn
+from rpmroute.route import exact_router
+from rpmroute.route.grid_router import GridRouter, RouteResult
+from rpmroute.route.pipeline import _rule_clearance_dsn, _rule_width_dsn
 
 # P1 and P2 are nearest each other, so the tree pairs them first; P3 sits
 # under the middle of that leg, 50 mm below it and 90 mm from either pin.