feat: build an AI agent from 0 to 1 -- 11 progressive sessions

- 11 sessions from basic agent loop to autonomous teams
- Python MVP implementations for each session
- Mental-model-first docs in en/zh/ja
- Interactive web platform with step-through visualizations
- Incremental architecture: each session adds one mechanism

.env.example

@@ -0,0 +1,61 @@
+# API Key (required)
+# Get yours at: https://console.anthropic.com/
+ANTHROPIC_API_KEY=sk-ant-xxx
+
+# Model ID (required)
+MODEL_ID=claude-sonnet-4-6
+
+# Base URL (optional, for Anthropic-compatible providers)
+# ANTHROPIC_BASE_URL=https://api.anthropic.com
+
+# =============================================================================
+#  Anthropic-compatible providers
+#
+#  Provider         MODEL_ID              SWE-bench  TB2     Base URL
+#  ---------------  --------------------  ---------  ------  -------------------
+#  Anthropic        claude-sonnet-4-6     79.6%      59.1%   (default)
+#  MiniMax          MiniMax-M2.5          80.2%        -     see below
+#  GLM (Zhipu)      glm-5                77.8%        -     see below
+#  Kimi (Moonshot)  kimi-k2.5            76.8%        -     see below
+#  DeepSeek         deepseek-chat        73.0%        -     see below
+#                   (V3.2)
+#
+#  SWE-bench = SWE-bench Verified (Feb 2026)
+#  TB2       = Terminal-Bench 2.0 (Feb 2026)
+# =============================================================================
+
+# ---- International ----
+
+# MiniMax          https://www.minimax.io
+# ANTHROPIC_BASE_URL=https://api.minimax.io/anthropic
+# MODEL_ID=MiniMax-M2.5
+
+# GLM (Zhipu)      https://z.ai
+# ANTHROPIC_BASE_URL=https://api.z.ai/api/anthropic
+# MODEL_ID=glm-5
+
+# Kimi (Moonshot)  https://platform.moonshot.ai
+# ANTHROPIC_BASE_URL=https://api.moonshot.ai/anthropic
+# MODEL_ID=kimi-k2.5
+
+# DeepSeek         https://platform.deepseek.com
+# ANTHROPIC_BASE_URL=https://api.deepseek.com/anthropic
+# MODEL_ID=deepseek-chat
+
+# ---- China mainland ----
+
+# MiniMax          https://platform.minimax.io
+# ANTHROPIC_BASE_URL=https://api.minimaxi.com/anthropic
+# MODEL_ID=MiniMax-M2.5
+
+# GLM (Zhipu)      https://open.bigmodel.cn
+# ANTHROPIC_BASE_URL=https://open.bigmodel.cn/api/anthropic
+# MODEL_ID=glm-5
+
+# Kimi (Moonshot)  https://platform.moonshot.cn
+# ANTHROPIC_BASE_URL=https://api.moonshot.cn/anthropic
+# MODEL_ID=kimi-k2.5
+
+# DeepSeek (no regional split, same endpoint globally)
+# ANTHROPIC_BASE_URL=https://api.deepseek.com/anthropic
+# MODEL_ID=deepseek-chat