feat: add editor tabs

README.md

@@ -28,6 +28,8 @@ Vamp starts in Normal mode. Press `i`, type text, then Esc to return to Normal.
 | Undo/redo in Normal | `u` / `U` (Shift+u) |
 | Split panes in Normal | `_` above/below; `\|` left/right; Option/Alt+h/j/k/l changes focus |
 | Close a pane | `:pane.close`; `:pane.force_close` explicitly discards exclusively displayed unsaved edits |
+| Open/switch tabs in Normal | `:tab.new` opens the current buffer; Ctrl+Option/Alt+h/l switches previous/next |
+| Close a tab | `:tab.close`; `:tab.force_close` explicitly discards exclusively displayed unsaved edits |
 | Delete/change whole lines in Normal | `dd` / `cc`; leading counts work (`3dd`, `2cc`) |
 | Search in Normal | `/`, type a literal query, Enter; `n`/`N` for next/previous |
 | Select/copy/cut | `v` characterwise or `V` whole rows, move to extend, then `y`/`d` in Visual |
@@ -48,7 +50,7 @@ Ruby configuration and plugins run with your account's filesystem/process permis
 
 ## Current limits
 
-- One visible buffer at a time; no splits/tabs or graphical frontend.
+- Terminal frontend only; no graphical frontend.
 - Modal editing, not full Vim compatibility: characterwise and linewise Visual selections and counted `dd`/`cc`, but no block selection, named registers, or general operator–motion grammar. Search is literal, case-sensitive, and single-line.
 - Native opt-in LSP supports diagnostics, go-to-definition, plain-text hover, manual primary-caret completion with snippet arguments, and automatic semantic highlighting—not rename, formatting, or code actions. Completion has no automatic popup or acceptance step; other carets are preserved and translated through the chosen edits. Snippet regex transforms and unresolved variables without defaults are omitted.
 - System clipboard access supports macOS and Linux. Separate clipboard mode keeps internal editing available on unsupported/headless environments.