chore: update AGENTS.md and CLAUDE.md for improved documentation

- Revised AGENTS.md to provide comprehensive guidance for AI coding assistants, including project overview, architecture, and development commands.
- Enhanced CLAUDE.md by adding the `auth` directory to the infrastructure section, clarifying the project's structure and components.
- Improved formatting and organization of both documentation files for better readability and usability.

CLAUDE.md

@@ -168,6 +168,7 @@ src/noteflow/
 ├── infrastructure/   # Implementations
 │   ├── audio/        # sounddevice capture, ring buffer, VU levels, playback, writer, reader
 │   ├── asr/          # faster-whisper engine, VAD segmenter, streaming, DTOs
+│   ├── auth/         # OIDC discovery, registry, presets
 │   ├── diarization/  # Session, assigner, engine (streaming: diart, offline: pyannote)
 │   ├── summarization/# CloudProvider, OllamaProvider, MockProvider, parsing, citation verifier, template renderer
 │   ├── triggers/     # Calendar, audio_activity, foreground_app providers
@@ -215,9 +216,15 @@ src/noteflow/
 │   ├── _mixins/      # Server-side gRPC mixins (see below)
 │   └── _client_mixins/# Client-side gRPC mixins
 ├── cli/              # CLI tools
+│   ├── __main__.py   # CLI entry point
 │   ├── retention.py  # Retention management
-│   ├── models/       # Model commands
-│   └── constants.py
+│   ├── constants.py  # CLI constants
+│   └── models/       # Model commands (package)
+│       ├── _download.py
+│       ├── _parser.py
+│       ├── _registry.py
+│       ├── _status.py
+│       └── _types.py
 └── config/           # Pydantic settings (NOTEFLOW_ env vars)
     ├── settings/     # _main.py, _features.py, _triggers.py, _calendar.py, _loaders.py
     └── constants/