simplify logger: fixed path ~/.opencode-matrix-plugin/, no fallback

logger.ts теперь всегда пишет в ~/.opencode-matrix-plugin/plugin.log.
setLogDir() стал no-op, удалён из index.ts.
Нет больше /tmp и fallback-файлов.

index.ts

@@ -4,7 +4,7 @@ import path from "path"
 import { MatrixBotClient } from "./matrix-client.js"
 import { SessionManager } from "./session-manager.js"
 import { loadConfig } from "./config-loader.js"
-import { setLogDir, log } from "./logger.js"
+import { log } from "./logger.js"
 
 // =============================================================================
 // Plugin data directory — uses the same default as matrix-client
@@ -298,7 +298,6 @@ async function v2Setup(ctx: any) {
     ? path.join(rawStorage, "plugin-data")
     : path.join(os.homedir(), ".local", "share", "opencode-matrix-bot", "plugin-data")
   ensureDataDir(dataDir)
-  setLogDir(dataDir)
 
   try {
     const { options } = await loadConfig(ctx.options)

logger.ts

@@ -1,23 +1,19 @@
 import fs from "fs"
+import os from "os"
 import path from "path"
 
-let LOG_DIR = "/tmp/opencode-matrix-plugin"
-let LOG_FILE = path.join(LOG_DIR, "plugin.log")
+const LOG_DIR = path.join(os.homedir(), ".opencode-matrix-plugin")
+const LOG_FILE = path.join(LOG_DIR, "plugin.log")
 
 export function setLogDir(dir: string): void {
-  LOG_DIR = dir
-  LOG_FILE = path.join(dir, "plugin.log")
+  // no-op: LOG_FILE is already set to the correct location
 }
 
 export function log(message: string): void {
   try {
     fs.mkdirSync(LOG_DIR, { recursive: true })
     fs.appendFileSync(LOG_FILE, `[${new Date().toISOString()}] ${message}\n`)
-  } catch (e) {
-    try {
-      fs.appendFileSync("/tmp/opencode-matrix-fallback.log", `[${new Date().toISOString()}] ${message}\n`)
-    } catch {
-      // silent fallback
-    }
+  } catch {
+    // silent
   }
 }