feat: disable capabilities by model provider (#19442)

## Why

Unsupported features must fail closed and Codex must not expose
OpenAI-hosted fallback paths when the active provider cannot support
them. In practice, Bedrock should not surface app connectors, MCP
servers, tool search/suggestions, image generation, web search, or JS
REPL until those paths are explicitly supported for that provider.

This PR moves that decision into provider-owned capability metadata
instead of scattering Bedrock-specific checks across callers.

## What changed

- Adds `ProviderCapabilities` to `codex-model-provider`, with default
support for existing providers and a Bedrock override that disables
unsupported launch surfaces.
- Adds `ToolCapabilityBounds` to `codex-tools` so provider capability
limits can clamp otherwise-enabled tool config.
- Applies capability bounds when building session and review-thread tool
config.
- Routes MCP/app connector configuration through
`McpManager::mcp_config`, which filters configured MCP servers and app
connectors based on the active provider.
- Updates app-server MCP list/read paths to use the filtered MCP config.
- Adds coverage for default provider capabilities, Bedrock disabled
capabilities, and optional tool-surface clamping.

## Testing

built locally and verified that bedrock responses api now return without
errors calling unsupported tools.

codex-rs/tools/src/tool_config.rs

@@ -94,6 +94,7 @@ pub struct ToolsConfig {
     pub web_search_tool_type: WebSearchToolType,
     pub image_gen_tool: bool,
     pub search_tool: bool,
+    pub namespace_tools: bool,
     pub tool_suggest: bool,
     pub exec_permission_approvals_enabled: bool,
     pub request_permissions_tool_enabled: bool,
@@ -214,6 +215,7 @@ impl ToolsConfig {
             web_search_tool_type: model_info.web_search_tool_type,
             image_gen_tool: include_image_gen_tool,
             search_tool: include_search_tool,
+            namespace_tools: true,
             tool_suggest: include_tool_suggest,
             exec_permission_approvals_enabled,
             request_permissions_tool_enabled,
@@ -241,6 +243,27 @@ impl ToolsConfig {
         self
     }
 
+    pub fn with_namespace_tools_capability(mut self, namespace_tools: bool) -> Self {
+        if !namespace_tools {
+            self.namespace_tools = false;
+        }
+        self
+    }
+
+    pub fn with_image_generation_capability(mut self, image_generation: bool) -> Self {
+        if !image_generation {
+            self.image_gen_tool = false;
+        }
+        self
+    }
+
+    pub fn with_web_search_capability(mut self, web_search: bool) -> Self {
+        if !web_search {
+            self.web_search_mode = None;
+        }
+        self
+    }
+
     pub fn with_spawn_agent_usage_hint(mut self, spawn_agent_usage_hint: bool) -> Self {
         self.spawn_agent_usage_hint = spawn_agent_usage_hint;
         self