Confirm and validate StormDNS profile imports

[poulcarlsen53]

What changed

This hardens the profile import path and the generated StormDNS TOML:

• stormdns:// links opened from Android now show a confirmation dialog before importing
• the dialog shows the profile name, server domain, and encryption method without revealing the key
• profile-link parsing is shared by preview and import so both paths validate the same data
• imported profile names, domains, and keys reject control characters; domains also reject whitespace
• TOML string escaping now handles newlines, tabs, carriage returns, backspace/form-feed, and other controls
• unit tests cover preview parsing, rejected unsafe imports, and TOML escaping

Why

A browsable stormdns:// link previously imported and selected a profile immediately. For a DNS/proxy/VPN client, that is a risky default because a crafted link can change the server a user routes traffic through. The TOML renderer also escaped quotes and backslashes only, so control characters could produce invalid or surprising config output.

Verification

• ./gradlew :app:testDebugUnitTest --tests shop.whitedns.client.model.WhiteDnsModelsTest --tests shop.whitedns.client.storm.StormDnsConfigRendererTest --no-daemon
• ./gradlew :app:compileDebugSources --no-daemon