Update built-in profiles to match website and migrate existing users

[dougborg]

Context

The built-in profiles hardcoded in the app are out of date compared to what's listed on deflock.me. Existing users who installed the app with the old defaults have stale copies in local storage.

Work

Update defaults

• Update the built-in profile definitions in lib/models/node_profile.dart to match the current deflock.me website listings (better tag sets, possibly new profiles)

Migrate existing users

• Add one-time migration code that runs on app launch to update existing users' saved profiles to the new versions
• Must not clobber any custom profiles the user created — only update profiles that match the old built-in defaults
• Migration should be idempotent and version-tracked (so it only runs once)

Relates to

• Update default profiles from the website on app launch #63 — longer-term goal of auto-syncing profiles from the website on every launch
• Improve profile discoverability and default coverage #103 — improving profile discoverability and default coverage

Files likely affected

• lib/models/node_profile.dart — built-in profile definitions
• Migration logic (likely in app init / AppState)

[dougborg]

Related: #63 proposes a longer-term solution to this same problem — auto-fetching the latest profiles from deflock.me on every app launch. If #63 is implemented, it would largely supersede this issue since the fetch-and-merge logic would handle both stale defaults and existing user migration.

These are two approaches to the same underlying problem (built-in profiles going stale). #142 is a one-time code fix + migration; #63 is an ongoing sync mechanism. Either works — leaving both open for discussion on which direction to go.