fix(hooks): propagate ephemeral sessionId through embedded tool contexts (#32273)

* fix(plugins): expose ephemeral sessionId in tool contexts for per-conversation isolation

The plugin tool context (`OpenClawPluginToolContext`) and tool hook
context (`PluginHookToolContext`) only provided `sessionKey`, which
is a durable channel identifier that survives /new and /reset.
Plugins like mem0 that need per-conversation isolation (e.g. mapping
Mem0 `run_id`) had no way to distinguish between conversations,
causing session-scoped memories to persist unbounded across resets.

Add `sessionId` (ephemeral UUID regenerated on /new and /reset) to:
- `OpenClawPluginToolContext` (factory context for plugin tools)
- `PluginHookToolContext` (before_tool_call / after_tool_call hooks)
- Internal `HookContext` for tool call wrappers

Thread the value from the run attempt through createOpenClawCodingTools
→ createOpenClawTools → resolvePluginTools and through the tool hook
wrapper.

Closes #31253

Made-with: Cursor

* fix(agents): propagate embedded sessionId through tool hook context

* test(hooks): cover sessionId in embedded tool hook contexts

* docs(changelog): add sessionId hook context follow-up note

* test(hooks): avoid toolCallId collision in after_tool_call e2e

---------

Co-authored-by: SidQin-cyber <sidqin0410@gmail.com>

src/agents/pi-tools.before-tool-call.integration.e2e.test.ts

@@ -122,6 +122,7 @@ describe("before_tool_call hook integration", () => {
     const tool = wrapToolWithBeforeToolCallHook({ name: "ReAd", execute } as any, {
       agentId: "main",
       sessionKey: "main",
+      sessionId: "ephemeral-main",
     });
     const extensionContext = {} as Parameters<typeof tool.execute>[3];
 
@@ -136,6 +137,7 @@ describe("before_tool_call hook integration", () => {
         toolName: "read",
         agentId: "main",
         sessionKey: "main",
+        sessionId: "ephemeral-main",
       },
     );
   });