chore(deps): bump bundled agents to latest (#936)

Bump Claude (claude-agent-sdk 0.3.211->0.3.212, claude-code 2.1.211->2.1.212,
lockstep) and OpenCode (sdk + cli 1.18.2->1.18.3). Codex and Cursor already
current; Kimi bump deferred (sandbox egress blocks GitHub asset SHA fetch).

Claude-Session: https://claude.ai/code/session_013nAqHLes3zGUrwdY3JWU4b

Co-authored-by: Claude <noreply@anthropic.com>

Author: dohooo

.changeset/bump-bundled-agents.md

@@ -0,0 +1,5 @@
+---
+"helmor": patch
+---
+
+Update the bundled Claude Code and OpenCode coding agents to their latest versions.

sidecar/bun.lock

@@ -14,12 +14,12 @@
 		"typecheck": "bunx tsc --noEmit"
 	},
 	"dependencies": {
-		"@anthropic-ai/claude-agent-sdk": "0.3.211",
-		"@anthropic-ai/claude-code": "2.1.211",
+		"@anthropic-ai/claude-agent-sdk": "0.3.212",
+		"@anthropic-ai/claude-code": "2.1.212",
 		"@cursor/sdk": "1.0.23",
 		"@openai/codex": "0.144.5",
-		"@opencode-ai/sdk": "1.18.2",
-		"opencode-ai": "1.18.2"
+		"@opencode-ai/sdk": "1.18.3",
+		"opencode-ai": "1.18.3"
 	},
 	"devDependencies": {
 		"@types/bun": "^1.3.11",