[BUG] VS Code extension: chat file links are never wired to the existing open_file bridge

**2 — binary files fail silently even once (1) is fixed.**

The host's `openFile` ends in

```js
vscode.window.showTextDocument(uri).then(cb) // no rejection handler
```

`showTextDocument` rejects for non-text files. With no `onRejected` and no `.catch`, the rejection is unhandled and the user sees nothing at all. So a link to a `.png` or `.pdf` stays dead even after the anchors are wired up.

### What Should Happen?

Clicking a file link should open the file — text in the editor, binary in its own viewer (image preview, PDF) — and a directory should reveal in the Explorer. Line anchors (`file.md#L42`, `#L42-L51`) should map to the `location` argument the host already accepts.

### Error Messages/Logs

None. The click is a silent no-op. Defect 2 produces an unhandled promise rejection from `showTextDocument` inside the extension host; nothing surfaces to the user.

### Steps to Reproduce

1. Ask Claude to create two files in a subfolder, e.g. `docs/note.md` and `docs/chart.png`.
2. Claude replies with `[note.md](docs/note.md)` and `[chart.png](docs/chart.png)` — the format its system prompt mandates.
3. Click either link in the chat panel. Nothing happens.
4. Same result with absolute paths, `file:///` URLs and directory paths (previously reported in #51015).

### Claude Model

Opus 5

### Is this a regression?

Yes, and a recurring one. #10846 was reported fixed in v2.1.4; broken again by v2.1.92 (#44713); again in 2.1.132 (#57100); still broken in **2.1.263**.

### Last Working Version

2.1.4 (per #10846)

### Claude Code Version

Extension `anthropic.claude-code-2.1.263-linux-x64`, VS Code 1.132.0

### Platform

VS Code extension (chat panel webview)

### Operating System

Debian 13 (trixie), KDE Plasma on X11

### Terminal/Shell

zsh — not relevant here; the defect is in the webview panel, not the CLI.

### Additional Information

**The desktop side is not at fault.** Verified locally before filing: VS Code installed from the native `.deb` (no Flatpak/Snap sandbox), `xdg-open` present, three `xdg-desktop-portal` processes running, an image handler registered for `image/png`. None of that is ever reached.

**Suggested fix — both parts are small:**

- *Webview:* on click of an anchor whose `href` carries no URL scheme and is not a `#` fragment, parse an optional `#L` / `#L-L` suffix into `location` and call the existing `openFile()`. External schemes keep their current behaviour.
- *Host:* give `showTextDocument(uri).then(cb)` a rejection handler that falls back to `vscode.commands.executeCommand("vscode.open", uri)`. One argument.

**Workaround** while this is open: a patch script that applies both fixes to the locally installed extension — idempotent, backs up per version, verifies with `node --check` and rolls back automatically on a syntax error, `--revert` to undo. It contains no Anthropic code; it locates the insertion points by pattern. → https://github.com/0nelight/claude-code-vscode-linkfix