[xvcezrqpbxtpzblrt]

Problem

On a cold start the window shows the web view's default white page until the host is up and React has painted: a white flash on every launch, longer on a slow disk.

Result

• The window is created hidden, and shown when the page says it has painted (a small ready signal from main.tsx once the first screen is committed), with a 12 s fallback in the page and a 15 s one in the shell so a failure still shows a window.
• While it is hidden, a second launch does not open a second window.
• The page remembers the window was hidden and asks the shell to show it, so a page that reloads later does not stay invisible.

Validation

• Built and run on Windows: window appears with the first painted screen, no white frame.
• cargo check clean; the Tauri capability for the show/focus commands is in tauri.conf.json.

Limits and the trade-off

• Not run on macOS or Linux, and not measured on a slow disk: the worst case is a blank (no window) for up to 12–15 s instead of a white window for a few seconds.
• If the owner prefers the default path untouched, an inline background colour and a static skeleton in index.html would remove the white flash without hiding the window; this branch is the more thorough version of that.

[xvcezrqpbxtpzblrt]

Superseded by #4606, which carries this change with the rest of the 0.2.7 branch. Closing so the review has one place.