fix(tools): resolve Read/Write/Edit paths against workspace directory

Previously, Read/Write/Edit tools used the global tool instances from
pi-coding-agent which had process.cwd() baked in at import time. Since
the gateway starts from /root/dev/ai/clawdbot, relative paths like
'SOUL.md' would incorrectly resolve there instead of the agent's
workspace (/root/clawd).

This fix:
- Adds workspaceDir option to createClawdbotCodingTools
- Creates fresh Read/Write/Edit tools bound to workspaceDir
- Adds cwd option to Bash tool defaults for consistency
- Passes effectiveWorkspace from pi-embedded-runner

Absolute paths and ~/... paths are unaffected. Sandboxed sessions
continue to use sandbox root as before.

Includes tests for Read/Write/Edit workspace path resolution.

src/agents/bash-tools.ts

@@ -61,6 +61,7 @@ export type BashToolDefaults = {
   elevated?: BashElevatedDefaults;
   allowBackground?: boolean;
   scopeKey?: string;
+  cwd?: string;
 };
 
 export type ProcessToolDefaults = {
@@ -202,7 +203,8 @@ export function createBashTool(
       }
 
       const sandbox = elevatedRequested ? undefined : defaults?.sandbox;
-      const rawWorkdir = params.workdir?.trim() || process.cwd();
+      const rawWorkdir =
+        params.workdir?.trim() || defaults?.cwd || process.cwd();
       let workdir = rawWorkdir;
       let containerWorkdir = sandbox?.containerWorkdir;
       if (sandbox) {