Add command to create a support bundle #751

If the user has difficulty with the plugin or connecting to their workspace, we should make it easy for them to collect all the information our support or engineering teams would need to diagnose.

Scope

Implement a Coder: Create Support Bundle command that:

1. Executes coder support bundle against the currently connected workspace via the CLI (needs coder/coder#21114 fix).
2. Shows progress using VS Code's progress notification (vscode.window.withProgress) while the bundle is being created.
3. Presents a save dialog (vscode.window.showSaveDialog) so the user can choose where to save the bundle file.
4. Optionally open the saved file — after saving, prompt the user with the option to open/reveal the file.
5. The command should be available in the Command Palette when connected to a workspace.

Additional data to include

Beyond what coder support bundle collects, the extension should also bundle:

• Plugin settings / configuration
• Plugin and relevant IDE logs

UX

• Command Palette: Coder: Create Support Bundle
• Progress notification while the bundle is created.
• Save dialog for the output file.
• Option to open/reveal the file after saving.

Follow-up

• AIGOV-193 — Proactive slowness detection (prompt users to run this command automatically when issues are detected).