restructure: move backend/ and layout/ into src/; convert README to org syntax; fix demo package conflict and alien-sap ioctl; update ROADMAP with v0.15.0; remove stale files

- Move backend/ and layout/ directories into src/
- Update all path references in ASD, scripts, docs
- Convert README.org from Markdown syntax to proper Org-mode
- Fix demo.lisp use-package conflict (both backend and input export #:read-event)
- Fix modern-backend TIOCGWINSZ ioctl alien type (alien-sap wrapper)
- Add v0.15.0 section to ROADMAP, update line count to 5760
- Add known gaps (suspend/resume-backend, slot modes) to v1.0.0 checklist
- Remove docs/plans/, debug-layout.lisp, system-index.txt, ci-watchdog.sh
- Move tangle.py to Hermes skill (org-babel-tangle)
- Add .gitignore for fasl files

cl-tty.asd

@@ -6,14 +6,14 @@
   :license "GPL-3.0"
   :depends-on (:sb-posix)
   :components
-  ((:module "backend"
+  ((:module "src/backend"
     :components
     ((:file "package")
      (:file "classes" :depends-on ("package"))
      (:file "simple" :depends-on ("package" "classes"))
      (:file "modern" :depends-on ("package" "classes"))
      (:file "detection" :depends-on ("package" "classes"))))
-   (:module "layout"
+   (:module "src/layout"
     :components
     ((:file "layout")))
    (:module "src/rendering"
@@ -58,11 +58,11 @@
   :description "Test suite for cl-tty"
   :depends-on (:cl-tty :fiveam)
   :components
-  ((:module "backend"
+  ((:module "src/backend"
     :components
     ((:file "tests")
      (:file "modern-tests" :depends-on ("tests"))))
-   (:module "layout"
+   (:module "src/layout"
     :components
     ((:file "tests")))
    (:module "src/components"