feat: vim p/P paste from system clipboard

Vim's default p/P pastes from its internal unnamed register, which
is useless when the text to translate lives in another app's
clipboard. Override both in normal mode to read navigator.clipboard
.readText() and insert at (after) or before the cursor.

Caveats: requires browser clipboard permission (prompted on first
use), HTTPS or localhost. Both already satisfied — finrod is served
over the wildcard TLS cert.

CHANGELOG.md

@@ -10,6 +10,7 @@ Versioning: [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 ### Added
 - Vim bindings in the input via CodeMirror 6 + `@replit/codemirror-vim` (loaded from esm.sh, no build step). Supports `i`/`Esc`, `hjkl`, word/line motions, `dd`/`yy`/`p`, undo/redo, `/` search, `:` command line. Auto-disabled on touch devices (detected via `(pointer: coarse)`) where modal editing fights the virtual keyboard.
 - `Shift-H` / `Shift-L` cycle focus across the page controls (source → target → model → editor → button) like `Shift-Tab` / `Tab`. Also overridden in vim normal mode (replacing vim's viewport-top/bottom default) so the same shortcut works to leave the editor.
+- `p` / `P` in vim normal mode paste from the system clipboard at / before the cursor (vim's default registers are skipped — the realistic source for a translator is another app, not an in-editor yank).
 - On page load, the model dropdown defaults to whichever model Ollama already has hot — skips the 5-15 s disk-reload pain on the first translation. After load it follows the user's manual selection.
 
 ### Changed