Bug: Cannot delete newly created page in PBIP format — `activePageName` in pages.json not synced wit

**Product:** Power BI Desktop
**Version:** June 2026 update (latest)
**File Format:** PBIP (Power BI Project)

**Description:**

When working with a report saved in PBIP format, newly created pages cannot be deleted via the right-click context menu. The right-click menu on the latest page tab only shows three options (New Page, Duplicate Page, Show Page as Tooltip) — the "Delete Page" option is missing.

**Root Cause:**

The `activePageName` field in `pages.json` is set to the name of the newly created page upon creation, but is never updated when the user performs any of the following UI actions:
- Switching to a different page by clicking its tab
- Setting another page as the landing page via "Set as landing page" option
- Any other navigation or page interaction

Since Power BI Desktop treats the page referenced by `activePageName` as the active page and enforces a rule that the active page cannot be deleted, the "Delete Page" option is permanently missing from the right-click menu for whichever page is listed as `activePageName`.

**Reproduction Steps:**

1. Open or create a report in Power BI Desktop and save it in PBIP format.
2. Create a new blank page (e.g., "Page 2").
3. Right-click the new page's tab → observe that the context menu only has 3 options; "Delete Page" is absent.
4. Switch to another page or set another page as the landing page.
5. Right-click the new page's tab again → "Delete Page" is still missing.
6. Open `pages.json` in the PBIP project folder and observe that `activePageName` still points to the newly created page despite all UI interactions.
7. Create yet another new page (e.g., "Page 3") → now "Page 2" can be deleted, but "Page 3" cannot.

**Expected Behavior:**

- `activePageName` should be updated when the user switches to a different page or sets a landing page, so the previously active page becomes deletable.
- Alternatively, the "Delete Page" option should be available for any page that is not the only page in the report, regardless of the `activePageName` state.

**Workaround:**

Manually edit `pages.json` in the PBIP project folder to change `activePageName` to a different page name, then reopen the file. After this change, the previously "stuck" page can be deleted normally.

**Impact:**

This is a breaking UX issue for users working in PBIP format. It creates confusion and forces users to either create dummy pages or manually edit JSON files to perform basic page management operations.