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/pi-embedded-runner.ts

@@ -849,6 +849,7 @@ export async function compactEmbeddedPiSession(params: {
           agentAccountId: params.agentAccountId,
           sessionKey: params.sessionKey ?? params.sessionId,
           agentDir,
+          workspaceDir: effectiveWorkspace,
           config: params.config,
           abortSignal: runAbortController.signal,
           modelProvider: model.provider,
@@ -1232,6 +1233,7 @@ export async function runEmbeddedPiAgent(params: {
             agentAccountId: params.agentAccountId,
             sessionKey: params.sessionKey ?? params.sessionId,
             agentDir,
+            workspaceDir: effectiveWorkspace,
             config: params.config,
             abortSignal: runAbortController.signal,
             modelProvider: model.provider,