refactor(opencode): native SDK tools, drop MCP, trim skills, expand telemetry

Reworks @mem0/opencode-plugin to expose memory operations as native OpenCode
tools (via the @opencode-ai/plugin `tool()` helper, backed by the mem0ai SDK)
instead of delegating to the remote MCP server. Skills load via the `config`
hook (`skills.paths`) instead of being copied into the project `.opencode/`.

- Drop MCP: remove the regex-based MCP tool interception, the bundled
  opencode.json MCP registration, and the cli.ts installer (mem0-opencode bin).
- Native tools: add_memory, search_memories, get_memories, get_memory,
  update_memory, delete_memory, delete_all_memories, delete_entities,
  list_entities, get_event_status.
- Trim skills 16 -> 8 (context-loader, dream, forget, health, peek, pin,
  remember, tour); remove import, export, memory-reviewer, mem0, list-projects,
  switch-project, stats, onboard. De-MCP/onboard wording in kept skills.
- Telemetry: emit the full shared plugin.* schema (adds user_prompt, bash_error,
  pre_compact, session_stop alongside session_start, tool_use); tool_use now
  fires from inside each native tool; add project_hash + os_version props.
- Fix duplicate error-search (single topK:6); correct the documented
  experimental.chat.messages.transform hook name.
- Bump to 0.2.0.

integrations/mem0-plugin/.opencode-plugin/telemetry.ts

@@ -13,11 +13,13 @@
  * installs without a key emit nothing). Disable with MEM0_TELEMETRY=false.
  *
  * Never sends: memory content, API keys, raw user/project IDs. Only sends:
- * event type, platform, plugin version, anonymized hash of the API key.
+ * event type, platform, plugin version, and anonymized hashes of the API key
+ * and project ID.
  */
 
 import { createHash } from "node:crypto";
 import { readFileSync } from "node:fs";
+import { release } from "node:os";
 
 const POSTHOG_API_KEY = "phc_hgJkUVJFYtmaJqrvf6CYN67TIQ8yhXAkWzUn9AMU4yX";
 const POSTHOG_HOST = "https://us.i.posthog.com/i/v0/e/";
@@ -62,6 +64,7 @@ export function buildEvent(
   eventType: string,
   properties: Record<string, unknown>,
   apiKey: string | undefined,
+  projectId?: string,
 ): Record<string, unknown> | null {
   if (!isTelemetryEnabled() || !apiKey) return null;
   return {
@@ -74,9 +77,14 @@ export function buildEvent(
       platform: "opencode",
       plugin_version: PLUGIN_VERSION,
       os: process.platform,
+      os_version: release(),
       sample_rate: 1.0,
       $process_person_profile: false,
       $lib: "posthog-node",
+      // Anonymized project segmentation, matching telemetry.py's project_hash.
+      ...(projectId
+        ? { project_hash: createHash("sha256").update(projectId).digest("hex") }
+        : {}),
     },
   };
 }
@@ -86,8 +94,9 @@ export function captureEvent(
   eventType: string,
   properties: Record<string, unknown>,
   apiKey: string | undefined,
+  projectId?: string,
 ): void {
-  const payload = buildEvent(eventType, properties, apiKey);
+  const payload = buildEvent(eventType, properties, apiKey, projectId);
   if (!payload) return;
   try {
     void fetch(POSTHOG_HOST, {