feat(aircoding): AirCoding V2 baseline — deterministic multi-agent architecture

Forked from OpenCode v1.17.4 with multi-agent system:
- 5 agents: aircoding, scheduler, worker, architect, reviewer
- Deterministic DAG scheduling engine (coordinator_tick)
- Tool whitelists as hard enforcement
- AirCoding validation plugin
- V1 requirements: C4 docs, ADR, AGENTS.md, debug-log.md
- Design documents in docs/

packages/docs/essentials/code.mdx

@@ -0,0 +1,35 @@
+---
+title: "Code blocks"
+description: "Display inline code and code blocks"
+icon: "code"
+---
+
+## Inline code
+
+To denote a `word` or `phrase` as code, enclose it in backticks (`).
+
+```
+To denote a `word` or `phrase` as code, enclose it in backticks (`).
+```
+
+## Code blocks
+
+Use [fenced code blocks](https://www.markdownguide.org/extended-syntax/#fenced-code-blocks) by enclosing code in three backticks and follow the leading ticks with the programming language of your snippet to get syntax highlighting. Optionally, you can also write the name of your code after the programming language.
+
+```java HelloWorld.java
+class HelloWorld {
+    public static void main(String[] args) {
+        System.out.println("Hello, World!");
+    }
+}
+```
+
+````md
+```java HelloWorld.java
+class HelloWorld {
+    public static void main(String[] args) {
+        System.out.println("Hello, World!");
+    }
+}
+```
+````