fix: use --data-urlencode for form-urlencoded curl snippets (#315)

| 🚥 Resolves CX-2935 |
| :------------------- |

## 🧰 Changes

Curl snippets for `application/x-www-form-urlencoded` endpoints were
using `--data` instead of `--data-urlencode`. This meant values with
special characters (spaces, ampersands, etc.) would break when
copy-paste and execute in a terminal.

The old code only checked if the param **name** needed encoding and
picked the flag based on that, while ignoring the value. The fix: always
use `--data-urlencode` for form-urlencoded params. It behaves
identically to `--data` when there's nothing to encode, so no downside.
Note that the form data values are never pre-encoded though, since
`oas-to-har` just calls `String()` on them.

This only affects the code snippet shown to developers, the "Try It"
executor uses `fetch-har` with `URLSearchParams` which already encodes
correctly.

## 🧬 QA & Testing

Find an endpoint with `application/x-www-form-urlencoded` content type,
check that the curl snippet uses `--data-urlencode` instead of `--data`

### Correct Example
```zsh
curl --request POST \
  --url https://httpbin.org/anything \
  --header 'content-type: application/x-www-form-urlencoded' \
  --data-urlencode 'foo=bar' \
  --data-urlencode 'query=hello world' \
  --data-urlencode 'filter=status=active&type=user'
```

```json
{
  "args": {}, 
  "data": "", 
  "files": {}, 
  "form": {
    "filter": "status=active&type=user", 
    "foo": "bar", 
    "query": "hello world"
  }, 
  "headers": {
    "Accept": "*/*", 
    "Content-Length": "62", 
    "Content-Type": "application/x-www-form-urlencoded", 
    "Host": "httpbin.org", 
    "User-Agent": "curl/8.7.1", 
    "X-Amzn-Trace-Id": "Root=1-69942c21-2119bf28086765883dfaa673"
  }, 
  "json": null, 
  "method": "POST", 
  "origin": "1.1.1.1", 
  "url": "https://httpbin.org/anything"
}
```

### Incorrect Example
```zsh
curl --request POST \
  --url https://httpbin.org/anything \
  --header 'content-type: application/x-www-form-urlencoded' \
  --data 'foo=bar' \
  --data 'query=hello world' \
  --data 'filter=status=active&type=user'
```

```json
{
  "args": {}, 
  "data": "", 
  "files": {}, 
  "form": {
    "filter": "status=active", 
    "foo": "bar", 
    "query": "hello world", 
    "type": "user"
  }, 
  "headers": {
    "Accept": "*/*", 
    "Content-Length": "56", 
    "Content-Type": "application/x-www-form-urlencoded", 
    "Host": "httpbin.org", 
    "User-Agent": "curl/8.7.1", 
    "X-Amzn-Trace-Id": "Root=1-69942d09-4ad6930b09907b011e840bec"
  }, 
  "json": null, 
  "method": "POST", 
  "origin": "1.1.1.1", 
  "url": "https://httpbin.org/anything"
}
```

Author: HugoHSun

src/targets/shell/curl/client.test.ts

@@ -88,6 +88,21 @@ runCustomFixtures({
       options: {},
       expected: 'urlencode.sh',
     },
+    {
+      it: 'should use --data-urlencode for form-urlencoded params with special characters in values',
+      input: {
+        ...applicationFormEncoded.log.entries[0].request,
+        postData: {
+          mimeType: 'application/x-www-form-urlencoded',
+          params: [
+            { name: 'query', value: 'hello world' },
+            { name: 'filter', value: 'status=active&type=user' },
+          ],
+        },
+      } as Request,
+      options: {},
+      expected: 'urlencode-values.sh',
+    },
     {
       it: 'should send JSON-encoded data with single quotes within a HEREDOC',
       input: {

src/targets/shell/curl/client.ts

@@ -138,11 +138,9 @@ export const curl: Client<CurlOptions> = {
       case 'application/x-www-form-urlencoded':
         if (postData.params) {
           postData.params.forEach(param => {
-            const unencoded = param.name;
             const encoded = encodeURIComponent(param.name);
-            const needsEncoding = encoded !== unencoded;
-            const name = needsEncoding ? encoded : unencoded;
-            const flag = binary ? '--data-binary' : needsEncoding ? '--data-urlencode' : arg('data');
+            const name = encoded !== param.name ? encoded : param.name;
+            const flag = binary ? '--data-binary' : '--data-urlencode';
             push(`${flag} ${quote(`${name}=${param.value}`)}`);
           });
         } else {

src/targets/shell/curl/fixtures/application-form-encoded.sh

@@ -1,5 +1,5 @@
 curl --request POST \
   --url https://httpbin.org/anything \
   --header 'content-type: application/x-www-form-urlencoded' \
-  --data foo=bar \
-  --data hello=world
+  --data-urlencode foo=bar \
+  --data-urlencode hello=world

src/targets/shell/curl/fixtures/custom-indentation.sh

@@ -3,4 +3,4 @@ curl --request POST \
 @--header 'accept: application/json' \
 @--header 'content-type: application/x-www-form-urlencoded' \
 @--cookie 'foo=bar; bar=baz' \
-@--data foo=bar
+@--data-urlencode foo=bar

src/targets/shell/curl/fixtures/full.sh

@@ -3,4 +3,4 @@ curl --request POST \
   --header 'accept: application/json' \
   --header 'content-type: application/x-www-form-urlencoded' \
   --cookie 'foo=bar; bar=baz' \
-  --data foo=bar
+  --data-urlencode foo=bar

src/targets/shell/curl/fixtures/short-options.sh

@@ -1 +1 @@
-curl -X POST 'https://httpbin.org/anything?foo=bar&foo=baz&baz=abc&key=value' -H 'accept: application/json' -H 'content-type: application/x-www-form-urlencoded' -b 'foo=bar; bar=baz' -d foo=bar
+curl -X POST 'https://httpbin.org/anything?foo=bar&foo=baz&baz=abc&key=value' -H 'accept: application/json' -H 'content-type: application/x-www-form-urlencoded' -b 'foo=bar; bar=baz' --data-urlencode foo=bar

src/targets/shell/curl/fixtures/urlencode-values.sh

@@ -0,0 +1,5 @@
+curl --request POST \
+  --url https://httpbin.org/anything \
+  --header 'content-type: application/x-www-form-urlencoded' \
+  --data-urlencode 'query=hello world' \
+  --data-urlencode 'filter=status=active&type=user'