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)

scripts/code-audit.lisp

@@ -32,11 +32,10 @@
           "src/components/dialog-package.lisp" "src/components/dialog.lisp"
           "src/components/dirty.lisp"
           "src/components/input-package.lisp" "src/components/input.lisp"
-          "src/components/keybindings.lisp"
-          "src/components/markdown-package.lisp" "src/components/markdown.lisp"
-          "src/components/mouse-package.lisp" "src/components/mouse.lisp"
-          "src/components/package.lisp" "src/components/render.lisp"
-          "src/components/scrollbox.lisp" "src/components/slot-package.lisp"
+           "src/components/keybindings.lisp"
+           "src/components/markdown-package.lisp" "src/components/markdown.lisp"
+           "src/components/package.lisp" "src/components/render.lisp"
+           "src/components/scrollbox.lisp" "src/components/slot-package.lisp"
           "src/components/slot.lisp" "src/components/tabbar.lisp"
           "src/components/text-input.lisp" "src/components/text.lisp"
           "src/components/textarea.lisp" "src/components/theme.lisp"
@@ -58,7 +57,6 @@
              "tests/scrollbox-tabbar-tests.lisp"
              "tests/markdown-tests.lisp"
              "tests/dialog-tests.lisp"
-             "tests/mouse-tests.lisp"
              "tests/slot-tests.lisp"
              "tests/framebuffer-tests.lisp"))
   (load f))