Clean up dead code and other low-hanging tech debt

A few low-risk cleanups found while combing through the extension:

- Remove the unused `getTimestampString()` from `src/utils.ts`. It's been
  dead since 2017 (`1b424000`), when "Add timestamps and log levels to all
  extension-side log messages" moved timestamping into the `Logger` and
  deleted its three call sites. It also had a latent bug: no zero-padding,
  so it rendered times like `[9:5:3]`.
- Remove the unused `getWindowsSystemPowerShellPath()` from
  `src/platform.ts`. It's been dead since #2238 (2019), which introduced
  `PowerShellExeFinder` and deleted the `System32PowerShellPath` /
  `SysnativePowerShellPath` / `SysWow64PowerShellPath` constants that
  called it. The same path is now built inline in `findWinPS()`, with
  proper bitness handling in `getSystem32Path()`.
- Replace `console.log` with `this.logger.writeDebug` in
  `writePidIfInDevMode` (`src/session.ts`), per our `ILogger` convention.
  While here, `await` the `fs.delete` it sits next to so the "Deleted PID
  file" message is actually true — previously it was a floating promise and
  the log ran before the delete resolved.
- Point the PSScriptAnalyzer rule docs link at `learn.microsoft.com`
  instead of `docs.microsoft.com` (`src/features/CodeActions.ts`); the old
  URL just 301s there anyway.

I left the Command Explorer's dead code alone since #5508 already rewrites
that file. Compile, lint, and format all pass; the touched code has no test
coverage so risk is low.

Drafted by Copilot (Claude Opus 4.8).

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Author: andyleejordan

src/features/CodeActions.ts

@@ -27,7 +27,7 @@ export class CodeActionsFeature implements vscode.Disposable {
 
     private async showRuleDocumentation(ruleId: string): Promise<void> {
         const pssaDocBaseURL =
-            "https://docs.microsoft.com/powershell/utility-modules/psscriptanalyzer/rules/";
+            "https://learn.microsoft.com/powershell/utility-modules/psscriptanalyzer/rules/";
 
         if (!ruleId) {
             this.log.writeWarning(

src/platform.ts

@@ -755,21 +755,6 @@ export class PowerShellExeFinder {
     }
 }
 
-export function getWindowsSystemPowerShellPath(
-    systemFolderName: string,
-): string | undefined {
-    if (process.env.windir === undefined) {
-        return undefined;
-    } else
-        return path.join(
-            process.env.windir,
-            systemFolderName,
-            "WindowsPowerShell",
-            "v1.0",
-            "powershell.exe",
-        );
-}
-
 interface IPossiblePowerShellExe extends IPowerShellExeDetails {
     exists(): Promise<boolean>;
     readonly suppressWarning: boolean;

src/session.ts

@@ -385,10 +385,10 @@ export class SessionManager implements Middleware {
         const fs = vscode.workspace.fs;
         const pid = (await pwshProcess.getPid())!.toString();
         await fs.writeFile(pidFilePath, Buffer.from(pid));
-        const deletePidOnExit = pwshProcess.onExited(() => {
+        const deletePidOnExit = pwshProcess.onExited(async () => {
             deletePidOnExit.dispose();
-            fs.delete(pidFilePath, { useTrash: false });
-            console.log(`Deleted PID file: ${pidFilePath}`);
+            await fs.delete(pidFilePath, { useTrash: false });
+            this.logger.writeDebug(`Deleted PID file: ${pidFilePath}`);
         });
         this.registeredCommands.push(deletePidOnExit);
         this.extensionContext.subscriptions.push(deletePidOnExit);

src/utils.ts

@@ -96,11 +96,6 @@ export async function readDirectory(
     return items.map(([name, _type]) => name);
 }
 
-export function getTimestampString(): string {
-    const time = new Date();
-    return `[${time.getHours()}:${time.getMinutes()}:${time.getSeconds()}]`;
-}
-
 export function sleep(ms: number): Promise<void> {
     return new Promise((resolve) => setTimeout(resolve, ms));
 }