docs: update README, wiki overview, index, log; add roles/code-review/pydantic wiki pages

- README: remove autogen/crewai references, add v2 architecture diagram,
  code-review scenario, cross-LLM config examples, roadmap
- wiki/overview: event-driven architecture, Pydantic v2, roadmap
- wiki/index: add entities/roles, concepts/code-review, packages/pydantic
- wiki/log: Phase 1 completion, code-review decision
- New: entities/roles.md, concepts/code-review.md, packages/pydantic.md

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

.wiki/packages/pydantic.md

@@ -0,0 +1,38 @@
+---
+title: Pydantic v2 Models
+type: package
+updated: 2026-05-04
+---
+
+# Pydantic v2 Models
+
+meeting-room uses Pydantic v2 for typed configuration, messages, and session data. All models are in `meeting_room/models.py`.
+
+## Config models
+
+| Model | Purpose | extra |
+|-------|---------|-------|
+| `ProviderConfig` | API provider (base_url, api_key) | forbid |
+| `RoleConfig` | Discussion role (name, provider, model, temperature, tools, system_prompt) | forbid |
+| `DefaultsConfig` | Default settings (max_rounds, language, framework, workdir) | ignore |
+| `DiscussionConfig` | Top-level config — direct counterpart of config.yaml | ignore |
+
+Key: `DiscussionConfig(**yaml_config)` works unchanged — feeds parsed YAML directly into the model.
+
+## Scenario model
+
+| Model | Purpose | extra |
+|-------|---------|-------|
+| `ScenarioConfig` | Loaded from .md/.yaml (name, participants, max_rounds, problem) | ignore |
+
+## Runtime models
+
+| Model | Purpose | extra |
+|-------|---------|-------|
+| `Message` | Single discussion message (role_id, name, content) | forbid |
+| `ToolCallRecord` | Tool call (id, name, arguments, result) | forbid |
+| `Session` | Full session (scenario, messages, tool_calls, created_at, updated_at) | ignore |
+
+## Tools field
+
+`RoleConfig.tools` accepts both `str` ("all", "readonly", etc.) and `list[str]` (["read_file", "web_search"]). A field validator coerces list items to strings.