Show and edit option values laid out as in named.conf

Values with blocks (logging, controls, ...) are shown over several lines
with indentation, and edited that way: the editor grows with its content,
Tab indents, Enter keeps the indentation. With a draft open, option tables
show the draft's values.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

internal/web/static/assets/style.css

@@ -443,6 +443,8 @@ footer.site a:hover { color: var(--accent); text-decoration-color: currentColor;
 .query-log li.pending code { opacity: 0.85; }
 .err-text { color: var(--err); }
 ul.plain { list-style: none; margin: 8px 0; padding: 0; }
+.code { tab-size: 4; }
+textarea.code { width: 100%; white-space: pre; overflow-wrap: normal; overflow-x: auto; }
 details.view-picker { position: relative; }
 details.view-picker summary { cursor: pointer; padding: 5px 8px; border: 1px solid var(--border); border-radius: var(--radius); background: var(--panel); min-width: 12em; max-width: 24em; overflow: hidden; text-overflow: ellipsis; white-space: nowrap; }
 details.view-picker[open] .view-picker-list { position: absolute; z-index: 20; top: calc(100% + 4px); left: 0; min-width: 14em; max-height: 260px; overflow-y: auto; display: flex; flex-direction: column; gap: 4px; padding: 8px 10px; background: var(--panel); border: 1px solid var(--border); border-radius: var(--radius); box-shadow: var(--shadow); }