feat(words): drawer follows emptiness — Insert when empty, Inspect when filled

User-clarified rule for the right drawer: when the current block is
empty, the drawer shows ONLY the constructors (Insert panel) — no
point in showing format/block-scope options on a blank line. When
the block has any content, the inspector for that content type
appears (paragraph + text-align, heading, image, code, etc.).

Implementation:

- New helper `isEmptyEditableTextBlock(block)` next to the slash
  command catalog. It returns true for paragraph / heading / quote /
  code-without-language whose single text child is the empty string.
  Atomic blocks (image / table / list) never qualify — they always
  carry structure.

- `WordsDrawerProvider.modes` derivation gates the scope-stack
  computation behind `!isEmptyTextBlock(currentNode)`. Empty text
  blocks fall through directly to `['default']` (just Insert);
  blocks with content build the scope stack as before (format /
  block / cell / row / table / list-item / list) and Insert
  collapses at the bottom of the stack.

- Atomic blocks (image / code with language) still push their
  scope unconditionally because their "content" lives in
  attributes, not children.

Before: clicking "+" → empty paragraph inserted → caret on it →
drawer showed `['block', 'default']` with Block expanded
(text-align controls for an empty line — useless), Insert
collapsed below.

After: clicking "+" → empty paragraph inserted → caret on it →
drawer shows `['default']` only (Insert expanded). As soon as the
user types a character, Block panel appears above with Insert
collapsed underneath.

152/152 soma words tests still pass; `npm run check` clean.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

src/uix/soma/components/words/words-provider.svelte.ts

@@ -2645,12 +2645,24 @@ export class WordsDrawerProvider {
 
 		const scopeStack: WordsDrawerMode[] = [];
 
+		// Emptiness gate — if the current block is a text-style block
+		// with no content, skip the scope entirely so the drawer only
+		// shows Insert (no point in formatting an empty line). Atomic
+		// blocks (image/table/code-with-language) always have content
+		// and pass through. Per user spec: "cuando el bloque está vacío
+		// solo se muestran los constructores; cuando ya tiene contenido,
+		// las opciones del objeto".
+		const currentIdx = sel?.anchor.path[0] ?? this.provider.selectedBlockIndex ?? -1;
+		const currentNode =
+			currentIdx >= 0 ? this.provider.document.children[currentIdx] : undefined;
+		const isEmptyTextBlock = isEmptyEditableTextBlock(currentNode);
+
 		// Atomic blocks (no inline format, no parent scopes)
 		if (block === 'image') {
 			scopeStack.push('image');
 		} else if (block === 'code') {
 			scopeStack.push('code');
-		} else if (sel) {
+		} else if (sel && !isEmptyTextBlock) {
 			// Inline-text format is the most specific scope. Only meaningful
 			// when there's a non-collapsed selection AND the current block
 			// can host inline marks (excludes 'code' which is plain text).
@@ -2941,6 +2953,39 @@ const DEFAULT_SLASH_COMMANDS = [
 	}
 ] as const satisfies readonly WordsSlashCommandItem[];
 
+/**
+ * "Empty text block" check used by the drawer's modes derivation
+ * (Insert ↔ Inspect rule): if the current block is a text-style
+ * block with no content, the drawer shows ONLY the Insert panel
+ * instead of the scope inspector. Paragraph / heading / quote /
+ * code-without-language qualify when their single text child is
+ * the empty string. Atomic blocks (image / table / list) never
+ * "look empty" — they always carry structure or content.
+ */
+function isEmptyEditableTextBlock(block: unknown): boolean {
+	if (!block || typeof block !== 'object') return false;
+	const b = block as {
+		type?: string;
+		language?: string;
+		children?: readonly { type?: string; text?: string }[];
+	};
+	if (
+		b.type !== 'paragraph' &&
+		b.type !== 'heading' &&
+		b.type !== 'quote' &&
+		b.type !== 'code'
+	) {
+		return false;
+	}
+	// A code block with a language already carries intent — even an
+	// empty body deserves the Code inspector so the user can change it.
+	if (b.type === 'code' && b.language) return false;
+	const kids = b.children ?? [];
+	if (kids.length !== 1) return false;
+	const only = kids[0];
+	return only?.type === 'text' && (only.text ?? '') === '';
+}
+
 function filterSlashCommandItems(query: string): readonly WordsSlashCommandItem[] {
 	const normalized = query.trim().toLowerCase();
 	if (!normalized) return DEFAULT_SLASH_COMMANDS;