v1.0.0: merge mouse → input — eliminate cl-tty.mouse package

The mouse-event struct was already in cl-tty.input. All mouse handling
logic (mouse-mixin, hit-test, selection, clipboard, link detection)
was in a separate cl-tty.mouse package. Moved everything into the
input package where the struct lives, eliminating one package boundary.

Changes:
- absorb mouse-mixin, handle-mouse-event, hit-test, selection struct,
  selection variables/functions, cell-link-at, open-link-at into
  text-input.org (tangled to input.lisp)
- update cl-tty.input defpackage with mouse exports
- mouse tests merged into INPUT-SUITE (appended to input-tests.lisp)
- delete mouse.org, mouse-package.lisp, mouse.lisp, mouse-tests.lisp
- update ASDF, run-all-tests.lisp, scripts to drop mouse references

All test suites pass at 100% (INPUT-SUITE: 102 tests, +6 from mouse)

cl-tty.asd

@@ -43,10 +43,7 @@
       ;; Dialog + Toast (v0.9.0)
       (:file "dialog-package" :depends-on ("package" "input-package"))
       (:file "dialog" :depends-on ("dialog-package" "dirty" "text-input"))
-     ;; Mouse support (v0.10.0)
-     (:file "mouse-package" :depends-on ("package" "input-package"))
-     (:file "mouse" :depends-on ("mouse-package" "dirty" "input"))
-     ;; Slot system (v0.11.0)
+      ;; Slot system (v0.11.0)
      (:file "slot-package" :depends-on ("package"))
      (:file "slot" :depends-on ("slot-package")))))
   :in-order-to ((test-op (test-op :cl-tty/test))))
@@ -72,8 +69,7 @@
       (:file "scrollbox-tabbar-tests" :pathname "../../tests/scrollbox-tabbar-tests")
       (:file "markdown-tests" :pathname "../../tests/markdown-tests")
       (:file "dialog-tests" :pathname "../../tests/dialog-tests")
-     (:file "mouse-tests" :pathname "../../tests/mouse-tests")
-      (:file "slot-tests" :pathname "../../tests/slot-tests")))
+       (:file "slot-tests" :pathname "../../tests/slot-tests")))
     (:module "src/rendering"
     :components
     ((:file "framebuffer-tests" :pathname "../../tests/framebuffer-tests"))))
@@ -88,8 +84,7 @@
                                  (:cl-tty-scrollbox-test "SCROLLBOX-SUITE")
                                  (:cl-tty-markdown-test)
                                  (:cl-tty-dialog-test "DIALOG-SUITE")
-                                 (:cl-tty-mouse-test "MOUSE-SUITE")
-                                (:cl-tty-slot-test "SLOT-SUITE")
+                                 (:cl-tty-slot-test "SLOT-SUITE")
                                 (:cl-tty-layout-test "LAYOUT-SUITE")
                                 (:cl-tty-modern-backend-test "MODERN-BACKEND-SUITE")
                                 (:cl-tty-framebuffer-test "FRAMEBUFFER-SUITE")))