fix: PVGS Mathlib compatibility — update imports + toolchain

Fixed Mathlib imports for v4.30.0-rc2:
- Mathlib.Data.Rat.Basic → Mathlib.Data.Rat.Defs + Lemmas
- Mathlib.Data.Rat.Order → (covered by Lemmas)
- Mathlib.Algebra.Order.AbsoluteValue → .Basic

Updated lean-toolchain to v4.30.0-rc2 (matches Mathlib).
Added SilverSightPVGS lean_lib to lakefile.

section4_rrc_kernel.lean compiles with 0 errors.
Build: SilverSight 3307 jobs, 0 errors.

formal/PVGS_DQ_Bridge/section4_rrc_kernel.lean

@@ -47,9 +47,9 @@
 -/
 
 import Mathlib.Data.Nat.Basic
-import Mathlib.Data.Rat.Basic
-import Mathlib.Data.Rat.Order
-import Mathlib.Algebra.Order.AbsoluteValue
+import Mathlib.Data.Rat.Defs
+import Mathlib.Data.Rat.Lemmas
+import Mathlib.Algebra.Order.AbsoluteValue.Basic
 import Mathlib.Tactic
 
 -- ============================================================

lakefile.lean

@@ -66,13 +66,11 @@ lean_lib «SilverSightRRC» where
     `RRCLib.RRCEmit
   ]
 
--- NOTE: PVGS_DQ_Bridge files depend on Mathlib modules not available
--- in SilverSight's pinned version. Needs Mathlib compatibility work.
--- lean_lib «SilverSightPVGS» where
---   srcDir := "formal"
---   roots := #[
---     `PVGS_DQ_Bridge.section4_rrc_kernel
---   ]
+lean_lib «SilverSightPVGS» where
+  srcDir := "formal"
+  roots := #[
+    `PVGS_DQ_Bridge.section4_rrc_kernel
+  ]
 
 lean_exe «rrc-emit-fixture» where
   root := `RrcEmitFixture

lean-toolchain

@@ -1 +1 @@
-leanprover/lean4:v4.32.0-rc1
+leanprover/lean4:v4.30.0-rc2