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/entities/roles.md

@@ -0,0 +1,45 @@
+---
+title: Discussion Roles
+type: entity
+updated: 2026-05-04
+---
+
+# Discussion Roles
+
+Roles define participants in a meeting-room discussion. Each role binds to a provider, model, temperature, tool set, and system prompt.
+
+## General discussion roles
+
+| Role | Purpose | Default tools |
+|------|---------|-------------|
+| moderator | Guide conversation, summarize, keep on-topic | none |
+| skeptic | Find weaknesses, ask hard questions, counter-argue | readonly |
+| idea_generator | Propose unconventional solutions, search web for inspiration | web |
+| analyst | Structure arguments, assess risks, propose action plans | all |
+
+## Code review roles
+
+| Role | Purpose | Default tools |
+|------|---------|-------------|
+| defender | Defend code decisions, explain rationale | readonly |
+| attacker | Ruthlessly find bugs, style violations, dead code | readonly |
+| security | Check vulnerabilities, injection, CVEs | web |
+| moderator | Structure review findings into CRITICAL/IMPORTANT/MINOR | none |
+
+## Role configuration
+
+```yaml
+roles:
+  my_role:
+    name: "Display Name"
+    provider: openai          # provider key from providers section
+    model: "gpt-4o"
+    temperature: 0.7          # 0.0 = deterministic, 1.0 = creative
+    tools: "readonly"         # tool set name or list ["read_file", "web_search"]
+    system_prompt: |
+      Your instructions here...
+```
+
+## Cross-LLM review
+
+Assign different `provider` values to roles so separate LLMs cross-check each other. The defender uses one model, the attacker uses another — each catches what the other misses.