Let extensions actually ask the user something

[Seungpyo1007]

Three shim functions ask the user something. All three answered without asking:

showQuickPick: () => Promise.resolve(undefined),
showInputBox:  () => Promise.resolve(undefined),
showInformationMessage: (msg, ..._items) => { toast(...); return Promise.resolve(undefined); },

In the VS Code contract undefined means the user cancelled. So an extension concluded it had been cancelled without a prompt ever appearing, and dropped whatever it was doing — no error, no toast. The third is the worst of them, because a toast does appear, so something looks like it happened. Meanwhile the near-universal

if (await vscode.window.showInformationMessage(msg, "Reload") === "Reload") { … }

was permanently false.

What it does now

All three open a real dialog. A pick returns the item the extension passed in, not a copy — extensions usually branch on a field they attached themselves. Supported: canPickMany, item arrays given as a Promise, matchOnDescription / matchOnDetail, password, and validateInput.

validateInput also runs when the dialog opens. An extension's initial value can already violate its own rule, and with no marking you have to press OK to find out why OK does not work.

A message with no buttons stays a toast. A notification should not block the flow — that distinction is the whole reason VS Code overloads one function.

Every prompt names the extension asking. If a dialog an extension opened reads as one the app opened, uninstalling the extension leaves you suspecting the app.

The filtering logic — normalize, match, cursor, validate — is a pure module with 26 tests.

Also: overlay z-index now comes from the table

The overlay table says a render's zIndex literal must equal its z. Saying it in a comment was not enough, and two had drifted: the confirm dialog is 233 in the table but rendered at 231, below the bundle installer at 232; the tour is 245 but rendered at 240, the same layer as the import dialog. Esc closes top-down by the table while the eye sees the opposite order — you press Esc at the dialog in front and the answer goes to the one hidden behind it. The render now reads overlayZ(id), so there is nowhere left for them to drift.

Verification

A real VS Code extension planted in the extensions folder, calling through require("vscode") — 18 of 18:

• a pick appears, names the extension, filters on description when asked to, and returns the original object ({label:"파랑", description:"cool", id:2})
• canPickMany returns ["a","c"] after Space-toggling two rows
• items handed over as a Promise resolve and are selectable
• showInputBox starts with the extension's value, shows the validation message straight away, refuses to close while invalid, clears the message when fixed, returns the typed string
• showInformationMessage(msg, "Reload", {title:"Later", isCloseAffordance:true}) renders both buttons and returns "Reload"
• a message with no buttons opens no dialog and resolves to undefined
• Esc closes the prompt and the extension receives undefined

716 tests, npm run typecheck clean.

Measured against the dev bundle — the harness needs localStorage to seed a workspace and file:// blocks it. Verification also required #40; without it the probe extension could not load at all.