[Platform] Add symfony/ai-agent to require-dev for bridges with OutputProcessors

Bridges with TokenOutputProcessor or SearchResultProcessor need
symfony/ai-agent as a dev dependency for their tests.

Affected bridges:
- Anthropic
- DeepSeek
- Gemini
- Mistral
- OpenAi
- Perplexity
- VertexAi

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Author: OskarStark

src/platform/src/Bridge/Anthropic/composer.json

@@ -23,7 +23,8 @@
         "symfony/ai-platform": "@dev"
     },
     "require-dev": {
-        "phpunit/phpunit": "^11.5.13"
+        "phpunit/phpunit": "^11.5.13",
+        "symfony/ai-agent": "@dev"
     },
     "minimum-stability": "dev",
     "autoload": {

src/platform/src/Bridge/DeepSeek/composer.json

@@ -28,7 +28,8 @@
     "symfony/ai-platform": "@dev"
   },
   "require-dev": {
-    "phpunit/phpunit": "^11.5.13"
+    "phpunit/phpunit": "^11.5.13",
+    "symfony/ai-agent": "@dev"
   },
   "minimum-stability": "dev",
   "autoload": {

src/platform/src/Bridge/Gemini/composer.json

@@ -23,7 +23,8 @@
         "symfony/ai-platform": "@dev"
     },
     "require-dev": {
-        "phpunit/phpunit": "^11.5.13"
+        "phpunit/phpunit": "^11.5.13",
+        "symfony/ai-agent": "@dev"
     },
     "minimum-stability": "dev",
     "autoload": {

src/platform/src/Bridge/Mistral/composer.json

@@ -23,7 +23,8 @@
         "symfony/ai-platform": "@dev"
     },
     "require-dev": {
-        "phpunit/phpunit": "^11.5.13"
+        "phpunit/phpunit": "^11.5.13",
+        "symfony/ai-agent": "@dev"
     },
     "minimum-stability": "dev",
     "autoload": {

src/platform/src/Bridge/OpenAi/composer.json

@@ -34,7 +34,8 @@
     "symfony/ai-platform": "@dev"
   },
   "require-dev": {
-    "phpunit/phpunit": "^11.5.13"
+    "phpunit/phpunit": "^11.5.13",
+    "symfony/ai-agent": "@dev"
   },
   "minimum-stability": "dev",
   "autoload": {

src/platform/src/Bridge/Perplexity/composer.json

@@ -23,7 +23,8 @@
         "symfony/ai-platform": "@dev"
     },
     "require-dev": {
-        "phpunit/phpunit": "^11.5.13"
+        "phpunit/phpunit": "^11.5.13",
+        "symfony/ai-agent": "@dev"
     },
     "minimum-stability": "dev",
     "autoload": {

src/platform/src/Bridge/VertexAi/composer.json

@@ -30,7 +30,8 @@
     "google/auth": "^1.47"
   },
   "require-dev": {
-    "phpunit/phpunit": "^11.5.13"
+    "phpunit/phpunit": "^11.5.13",
+    "symfony/ai-agent": "@dev"
   },
   "minimum-stability": "dev",
   "autoload": {