Add Copilot skill architecture with 10 skills, 2 agents, and shared infra

Introduce .github/skills/ with solve, prove, optimize, simplify,
encode, explain, benchmark, memory-safety, static-analysis, and
deeptest skills. Each skill follows a SKILL.md + scripts/ pattern
with Python scripts backed by a shared SQLite logging library
(z3db.py). Two orchestrator agents (z3-solver, z3-verifier) route
requests to the appropriate skills.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

.github/skills/simplify/scripts/simplify.py

@@ -0,0 +1,83 @@
+#!/usr/bin/env python3
+"""
+simplify.py: apply Z3 tactics to simplify an SMT-LIB2 formula.
+
+Usage:
+    python simplify.py --formula "(assert (and (> x 0) (> x 0)))" --vars "x:Int"
+    python simplify.py --file formula.smt2 --tactics "simplify,solve-eqs"
+"""
+
+import argparse
+import sys
+from pathlib import Path
+
+sys.path.insert(0, str(Path(__file__).resolve().parent.parent.parent / "shared"))
+from z3db import Z3DB, run_z3, setup_logging
+
+
+DEFAULT_TACTICS = "simplify,propagate-values,ctx-simplify"
+
+
+def build_tactic_formula(base_formula: str, tactics: str) -> str:
+    tactic_list = [t.strip() for t in tactics.split(",")]
+    if len(tactic_list) == 1:
+        tactic_expr = f"(then {tactic_list[0]} skip)"
+    else:
+        tactic_expr = "(then " + " ".join(tactic_list) + ")"
+    return base_formula + f"\n(apply {tactic_expr})\n"
+
+
+def build_formula_from_parts(formula_str: str, vars_str: str) -> str:
+    lines = []
+    if vars_str:
+        for v in vars_str.split(","):
+            v = v.strip()
+            name, sort = v.split(":")
+            lines.append(f"(declare-const {name.strip()} {sort.strip()})")
+    lines.append(formula_str)
+    return "\n".join(lines)
+
+
+def main():
+    parser = argparse.ArgumentParser(prog="simplify")
+    parser.add_argument("--formula")
+    parser.add_argument("--vars")
+    parser.add_argument("--file")
+    parser.add_argument("--tactics", default=DEFAULT_TACTICS)
+    parser.add_argument("--timeout", type=int, default=30)
+    parser.add_argument("--z3", default=None)
+    parser.add_argument("--db", default=None)
+    parser.add_argument("--debug", action="store_true")
+    args = parser.parse_args()
+
+    setup_logging(args.debug)
+
+    if args.file:
+        base = Path(args.file).read_text()
+    elif args.formula:
+        base = build_formula_from_parts(args.formula, args.vars or "")
+    else:
+        parser.error("provide --formula or --file")
+        return
+
+    formula = build_tactic_formula(base, args.tactics)
+
+    db = Z3DB(args.db)
+    run_id = db.start_run("simplify", formula)
+
+    result = run_z3(formula, z3_bin=args.z3, timeout=args.timeout, debug=args.debug)
+
+    status = "success" if result["exit_code"] == 0 else "error"
+    db.log_formula(run_id, formula, status)
+    db.finish_run(run_id, status, result["duration_ms"], result["exit_code"])
+
+    print(result["stdout"])
+    if result["stderr"] and result["exit_code"] != 0:
+        print(result["stderr"], file=sys.stderr)
+
+    db.close()
+    sys.exit(0 if result["exit_code"] == 0 else 1)
+
+
+if __name__ == "__main__":
+    main()