literate: add org sources for orphan test files, update README

- Create org/integration-tests.org (15 blocks, per-test prose)
- Add Markdown tests section to org/markdown-renderer.org (11 test blocks)
- Delete deprecated src/components/input-tests.lisp stub
- Update README.org: tree diagram, literate programming section,
  development commands, remove stale test counts

All 13 test suites pass at 100%. Zero .lisp files without org origin.

src/components/input-tests.lisp

@@ -1,12 +0,0 @@
-;; This file is deprecated. Tests moved to tests/input-tests.lisp.
-;; Kept as placeholder to prevent confusion with stale copies.
-(defpackage :cl-tty-input-test
-  (:use :cl :fiveam :cl-tty.backend :cl-tty.box :cl-tty.layout :cl-tty.input)
-  (:export #:run-tests))
-(in-package :cl-tty-input-test)
-
-(defun run-tests ()
-  (warn "src/components/input-tests.lisp is deprecated. Use tests/input-tests.lisp instead.")
-  (let ((result (run 'input-suite)))
-    (fiveam:explain! result)
-    (uiop:quit 0)))