Add dynamic() support to prompt.form() plugin API

- prompt.form() inputs can now have dynamic() callbacks that update
  reactively when form values change (same pattern as auth/template plugins)
- Changed PromptFormRequest routing from one-shot to bidirectional events
- Added PromptFormResponse.done field to distinguish intermediate updates
- Added optional size (enum) to PromptFormRequest for dialog sizing
- Added optional rows to FormInputEditor for fixed height editors
- New httpsnippet plugin: generates code snippets with dynamic language
  and library selectors that update the code preview in real-time

src-web/components/DynamicForm.tsx

@@ -360,8 +360,9 @@ function EditorArg({
         className={classNames(
           'border border-border rounded-md overflow-hidden px-2 py-1',
           'focus-within:border-border-focus',
-          'max-h-[10rem]', // So it doesn't take up too much space
+          !arg.rows && 'max-h-[10rem]', // So it doesn't take up too much space
         )}
+        style={arg.rows ? { height: `${arg.rows * 1.4 + 0.75}rem` } : undefined}
       >
         <Editor
           id={id}

src-web/components/core/Prompt.tsx

@@ -1,6 +1,6 @@
 import type { FormInput, JsonPrimitive } from '@yaakapp-internal/plugins';
 import type { FormEvent } from 'react';
-import { useCallback, useRef, useState } from 'react';
+import { useCallback, useEffect, useRef, useState } from 'react';
 import { generateId } from '../../lib/generateId';
 import { DynamicForm } from '../DynamicForm';
 import { Button } from './Button';
@@ -12,16 +12,21 @@ export interface PromptProps {
   onResult: (value: Record<string, JsonPrimitive> | null) => void;
   confirmText?: string;
   cancelText?: string;
+  onValuesChange?: (values: Record<string, JsonPrimitive>) => void;
+  onInputsUpdated?: (cb: (inputs: FormInput[]) => void) => void;
 }
 
 export function Prompt({
   onCancel,
-  inputs,
+  inputs: initialInputs,
   onResult,
   confirmText = 'Confirm',
   cancelText = 'Cancel',
+  onValuesChange,
+  onInputsUpdated,
 }: PromptProps) {
   const [value, setValue] = useState<Record<string, JsonPrimitive>>({});
+  const [inputs, setInputs] = useState<FormInput[]>(initialInputs);
   const handleSubmit = useCallback(
     (e: FormEvent<HTMLFormElement>) => {
       e.preventDefault();
@@ -30,6 +35,16 @@ export function Prompt({
     [onResult, value],
   );
 
+  // Register callback for external input updates (from plugin dynamic resolution)
+  useEffect(() => {
+    onInputsUpdated?.(setInputs);
+  }, [onInputsUpdated]);
+
+  // Notify of value changes for dynamic resolution
+  useEffect(() => {
+    onValuesChange?.(value);
+  }, [value, onValuesChange]);
+
   const id = `prompt.form.${useRef(generateId()).current}`;
 
   return (