Core tools now properly use the cwd passed to createAgentSession().
Added tool factory functions for SDK users who specify custom cwd with explicit tools.
Fixes#279
- SettingsManager now loads .pi/settings.json from cwd (project settings)
- Project settings merge with global settings (deep merge for objects)
- Setters only modify global settings, project settings are read-only
- Add static factories: SettingsManager.create(cwd?, agentDir?), SettingsManager.inMemory(settings?)
- Add applyOverrides() for programmatic overrides
- Replace 'settings' option with 'settingsManager' in CreateAgentSessionOptions
- Update examples to use new pattern
Incorporates PR #276 approach