Add theorem prover docs page with Phase 2 constraint solving

- prove.sx Phase 2: bounded model checking with 34 algebraic properties
  (commutativity, associativity, distributivity, inverses, bounds, transitivity)
- prove.sx generates SMT-LIB for unbounded Z3 verification via z3-expr
- New docs page /plans/theorem-prover with live results (91/91 sat, 34/34 verified)
- Page helper runs both proof phases and returns structured data
- Parser: re-add ' quote syntax (removed by prior edit)
- Load prove.sx alongside z3.sx at startup

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

shared/sx/components.py

@@ -28,7 +28,7 @@ def _load_sx_libraries() -> None:
     """Load self-hosted SX libraries from the ref directory."""
     from .jinja_bridge import register_components
     ref_dir = os.path.join(os.path.dirname(__file__), "ref")
-    for name in ("z3.sx",):
+    for name in ("z3.sx", "prove.sx"):
         path = os.path.join(ref_dir, name)
         if os.path.exists(path):
             with open(path, encoding="utf-8") as f: