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

src/backend/package.lisp

@@ -0,0 +1,33 @@
+(defpackage :cl-tty.backend
+  (:use :cl)
+  (:export
+   ;; Backend classes
+   #:backend #:simple-backend
+   ;; Lifecycle
+   #:initialize-backend #:shutdown-backend
+   #:backend-size #:backend-write #:backend-clear
+   ;; Drawing
+   #:draw-text #:draw-border #:draw-rect
+   #:draw-link #:draw-ellipsis
+   ;; Cursor
+   #:cursor-move #:cursor-hide #:cursor-show #:cursor-style
+   ;; Sync
+   #:begin-sync #:end-sync
+   ;; Input
+   #:read-event #:enable-mouse #:enable-bracketed-paste
+   ;; Queries
+   #:capable-p
+   ;; Constructors
+   #:make-simple-backend
+   ;; Modern backend
+   #:modern-backend #:make-modern-backend
+   ;; Detection
+   #:detect-backend #:*detected-backend*
+   ;; Theme color resolution (populated by theme system)
+   #:*theme-colors*
+   ;; Internal (for testing)
+   #:sgr-fg #:sgr-bg #:sgr-attr
+   #:cursor-move-escape #:cursor-style-escape
+   #:decicm-begin #:decicm-end #:osc8-link
+   #:hex-to-rgb #:border-char))
+(in-package :cl-tty.backend)