refactor: restructure workspace file organization (#121) (#122)

## Path Changes
- audit.log: memory/audit.log → log/audit.log
- projects.json: memory/projects.json → projects/projects.json
- prompts: roles/<project>/<role>.md → projects/prompts/<project>/<role>.md

## Files Updated
- lib/audit.ts - new audit log path
- lib/projects.ts - new projects.json path
- lib/dispatch.ts - new prompt instructions path
- lib/tools/project-register.ts - prompt scaffolding path
- lib/setup/workspace.ts - workspace scaffolding paths
- lib/context-guard.ts - projects.json path
- lib/tools/setup.ts - tool description
- lib/templates.ts - AGENTS.md template path references

## Documentation Updated
- README.md
- docs/ARCHITECTURE.md
- docs/ONBOARDING.md
- docs/QA_WORKFLOW.md
- docs/ROADMAP.md
- docs/TESTING.md

Addresses issue #121

lib/context-guard.ts

@@ -140,7 +140,7 @@ You're in a **Telegram/WhatsApp group** bound to ${context.projectName ? `projec
 }
 
 /**
- * Find project name by matching groupId in memory/projects.json.
+ * Find project name by matching groupId in projects/projects.json.
  * The groupId (Telegram or WhatsApp) is the KEY in the projects Record.
  */
 async function findProjectByGroupId(
@@ -150,7 +150,7 @@ async function findProjectByGroupId(
   if (!workspaceDir) return undefined;
 
   try {
-    const projectsPath = path.join(workspaceDir, "memory", "projects.json");
+    const projectsPath = path.join(workspaceDir, "projects", "projects.json");
     const raw = await fs.readFile(projectsPath, "utf-8");
     const data = JSON.parse(raw) as {
       projects: Record<string, { name: string }>;