docs: add comprehensive README with usage guide and architecture

docs: mark all wmux v1 acceptance criteria complete

feat(cli): complete CLI-server integration for all commands

feat(app): integrate full TUI event loop with all widgets

test: add comprehensive integration test suite

feat(ui): add help overlay (C-w ?)

feat(cli): add CLI subcommands (new, attach, list, kill)

feat(config): add TOML configuration system

feat(copy): add mouse selection and clipboard integration

feat(input): add mouse support for focus and selection

feat(input): add resize mode for pane resizing

feat(input): add pane navigation with hjkl and arrows

feat(input): add leader key state machine and keybindings

feat(ui): add TUI components (terminal view, layout, tabs, statusbar)

feat(server): add client connection handling with handshake