skill-loader export fix + TUI config panel + provider test + slot descriptions

- Fix skill loader export: unintern before import (handle existing symbols)
- Add ignore-errors around export (handle package conflicts)
- Add test-provider-connection (live API key testing for TUI config)
- Add *slot-descriptions* with per-slot explanations for TUI config screen
- Rewrite gateway-tui with expanding minibuffer config panel (F2 toggle)
- Fix skill loader exclusion list: add system-model-router
- All org files updated with proper prose

org/core-skills.org

@@ -327,8 +327,7 @@ The validation step is critical: invalid Lisp in an org block would crash the lo
                       (setf (gethash (symbol-name sym) seen) t)
                       (incf exported)
                       (let ((existing (find-symbol (symbol-name sym) target-pkg)))
-                        (when (and existing (not (eq existing sym)))
-                          (unintern existing target-pkg)))
+                        (when existing (unintern existing target-pkg)))
                       (import sym target-pkg)
                       (export sym target-pkg)))
                   (log-message "LOADER: Exported ~a symbols from ~a to :PASSEPARTOUT"
@@ -376,10 +375,9 @@ The same jailed package and symbol export process applies.
                 (setf (gethash (symbol-name sym) seen) t)
                 (incf exported)
                 (let ((existing (find-symbol (symbol-name sym) target-pkg)))
-                  (when (and existing (not (eq existing sym)))
-                    (unintern existing target-pkg)))
+                  (when existing (unintern existing target-pkg)))
                 (import sym target-pkg)
-                (export sym target-pkg)))
+                (ignore-errors (export sym target-pkg))))
             (log-message "LOADER: Exported ~a symbols from ~a to :PASSEPARTOUT"
                          exported (package-name (find-package pkg-name))))
           (setf (skill-entry-status entry) :ready))