feat: mount user repo as read-only with writable shannon overlay (#273)

* feat: mount user repo as read-only with deliverables bind-mount overlay

* feat: add playground and .playwright-cli overlay mounts

* feat: add filesystem context to pipeline-testing prompts

* fix: use explicit REPO_PATH in filesystem prompt for clarity

* fix: update filesystem prompts with playground notes and absolute screenshot paths

* feat: namespace writable overlays under .shannon/ to avoid polluting host repo

* refactor: rename playground to scratchpad

* fix: redirect playwright-cli output to writable .shannon/ overlay

* fix: pre-create .shannon/ overlay mount points for Linux compatibility

* fix: exclude nested node_modules and dist from Docker build context

* fix: enforce LF line endings for shell scripts on Windows

.dockerignore

@@ -1,5 +1,5 @@
 # Node.js
-node_modules/
+**/node_modules/
 npm-debug.log*
 yarn-debug.log*
 yarn-error.log*
@@ -49,8 +49,7 @@ Thumbs.db
 # CLI package (runs on host, not in container)
 # Keep apps/cli/package.json so pnpm workspaces resolve
 apps/cli/src/
-apps/cli/dist/
-apps/worker/dist/
+**/dist/
 apps/cli/infra/
 apps/cli/tsconfig.json
 apps/cli/tsdown.config.ts