fix: improve Windows compatibility and fix event listener issues (#1102)

Replace platform-specific 'which'/'where' commands with cross-platform Bun.which() API to fix Windows compatibility issues and simplify code.

Fixes:
- #1027: Comment-checker binary crashes on Windows (missing 'check' subcommand)
- #1036: Session-notification listens to non-existent events
- #1033: Infinite loop in session notifications
- #599: Doctor incorrectly reports OpenCode as not installed on Windows
- #1005: PowerShell path detection corruption on Windows

Changes:
- Use Bun.which() instead of spawning 'which'/'where' commands
- Add 'check' subcommand to comment-checker invocation
- Remove non-existent event listeners (session.updated, message.created)
- Prevent notification commands from resetting their own state
- Fix edge case: clear notifiedSessions if activity occurs during notification

All changes are cross-platform compatible and tested on Windows/Linux/macOS.

src/cli/doctor/checks/dependencies.ts

@@ -3,11 +3,9 @@ import { CHECK_IDS, CHECK_NAMES } from "../constants"
 
 async function checkBinaryExists(binary: string): Promise<{ exists: boolean; path: string | null }> {
   try {
-    const proc = Bun.spawn(["which", binary], { stdout: "pipe", stderr: "pipe" })
-    const output = await new Response(proc.stdout).text()
-    await proc.exited
-    if (proc.exitCode === 0) {
-      return { exists: true, path: output.trim() }
+    const path = Bun.which(binary)
+    if (path) {
+      return { exists: true, path }
     }
   } catch {
     // intentionally empty - binary not found

src/cli/doctor/checks/opencode.ts

@@ -55,16 +55,9 @@ export function buildVersionCommand(
 export async function findOpenCodeBinary(): Promise<{ binary: string; path: string } | null> {
   for (const binary of OPENCODE_BINARIES) {
     try {
-      const lookupCommand = getBinaryLookupCommand(process.platform)
-      const proc = Bun.spawn([lookupCommand, binary], { stdout: "pipe", stderr: "pipe" })
-      const output = await new Response(proc.stdout).text()
-      await proc.exited
-      if (proc.exitCode === 0) {
-        const paths = parseBinaryPaths(output)
-        const selectedPath = selectBinaryPath(paths, process.platform)
-        if (selectedPath) {
-          return { binary, path: selectedPath }
-        }
+      const path = Bun.which(binary)
+      if (path) {
+        return { binary, path }
       }
     } catch {
       continue