feat: TypeScript SDK (agentlens-sdk) and OpenCode plugin (opencode-agentlens)

- packages/sdk-ts: BatchTransport, TraceBuilder, models, decision helpers
  Zero external deps, native fetch, ESM+CJS output
- packages/opencode-plugin: OpenCode plugin with hooks for:
  - Session lifecycle (create/idle/error/delete/diff)
  - Tool execution capture (before/after -> TOOL_CALL spans + TOOL_SELECTION decisions)
  - LLM call tracking (chat.message -> LLM_CALL spans with model/provider)
  - Permission flow (permission.ask -> ESCALATION decisions)
  - File edit events
  - Model cost estimation (Claude, GPT-4o, o3-mini pricing)

packages/opencode-plugin/src/config.ts

@@ -0,0 +1,41 @@
+export interface PluginConfig {
+  apiKey: string;
+  endpoint: string;
+  enabled: boolean;
+  /** Opt-in: capture full message content in traces */
+  captureContent: boolean;
+  /** Maximum characters for tool output before truncation */
+  maxOutputLength: number;
+  /** Milliseconds between automatic flushes */
+  flushInterval: number;
+  /** Maximum traces per batch */
+  maxBatchSize: number;
+}
+
+export function loadConfig(): PluginConfig {
+  const apiKey = process.env["AGENTLENS_API_KEY"] ?? "";
+
+  if (!apiKey) {
+    console.warn(
+      "[agentlens] AGENTLENS_API_KEY not set — plugin will be disabled",
+    );
+  }
+
+  return {
+    apiKey,
+    endpoint:
+      process.env["AGENTLENS_ENDPOINT"] ?? "https://agentlens.vectry.tech",
+    enabled: (process.env["AGENTLENS_ENABLED"] ?? "true") === "true",
+    captureContent:
+      (process.env["AGENTLENS_CAPTURE_CONTENT"] ?? "false") === "true",
+    maxOutputLength: parseInt(
+      process.env["AGENTLENS_MAX_OUTPUT_LENGTH"] ?? "2000",
+      10,
+    ),
+    flushInterval: parseInt(
+      process.env["AGENTLENS_FLUSH_INTERVAL"] ?? "5000",
+      10,
+    ),
+    maxBatchSize: parseInt(process.env["AGENTLENS_BATCH_SIZE"] ?? "10", 10),
+  };
+}