[antonreshetov]

closes #972

Problem

storage.vaultPath defaults to null. The renderer sends pref ?? '' as the vault token, and the main process compared that token with the resolved getVaultPath(). For users on the default vault these values never match, so every request was rejected as stale. Since v6.0.0, image paste and drop in notes has silently failed, along with several other actions guarded the same way. This affects all platforms, not only Windows.

Fix

• New vaultIdentity() in runtime/paths.ts returns the raw preference token (storage.vaultPath ?? ''). All stale checks between renderer and main now compare against this token.
• getVaultPath() is used only for filesystem paths and HTTP session keys.
• On the renderer side, comparisons normalize the preference with ?? '' so they match the token main uses.

Affected flows

• Notes: image paste, drop and file picker
• AI folder icon change and its undo
• AI tasks cleanup undo
• Rendered artifact export
• HTTP request preview now picks up session variables
• AI HTTP actions now read and clear the user's live HTTP session instead of a separate empty one, so they no longer reset it
• The HTTP UI picks up saved execution results again

Tests

Added regression cases for the default vault (null preference) to each touched test suite.