Improve license activation system to improve Pro feature licensing architecture

[shadowbipnode]

Current licensing system validates signatures but does not yet fully prevent widespread key sharing.

Planned improvements:

• activation tracking
• device fingerprinting
• activation limits
• license revocation support
• abuse detection
• offline activation fallback
• privacy-conscious validation system

[shadowbipnode]

Moving this to v1.5.0-beta.

License anti-sharing protections are important for future commercialization, but they are not required for the current operational beta phase.

The focus of v1.4.0-beta is workflow stabilization, packaging, UX polish and infrastructure-oriented operational tooling.

[shadowbipnode]

Re-scope this issue from a simple activation fix into a proper Pro licensing architecture.

New direction:

• Keep SysAI core open source.
• Move commercial license generation, activation tracking, and admin tooling into a private/closed licensing layer.
• Use an open-core model rather than trying to hide licensing logic inside the public Electron app.

Proposed architecture:

• Public repo keeps only the license client, public verification key, feature gates, and entitlement checks.
• Private repo/service handles license generation, Telegram/admin management, device activation limits, revocation, and private signing keys.
• First activation should contact a license server.
• License server should enforce max activations per license.
• Client should store signed entitlement data locally for offline/grace use.
• Free/core functionality should continue working even if licensing fails.
• Pro features should gracefully disable when license is invalid, expired, revoked, or activation limit is reached.

Suggested server-side API:

• POST /activate
• POST /validate
• POST /deactivate
• optional POST /refresh

License payload should include:

• license_id
• plan
• issued_at
• expires_at
• max_activations
• enabled_features
• device activation metadata
• signature

Security principles:

• Never expose private signing keys in the open-source app.
• Do not rely on frontend-only checks for commercial enforcement.
• Treat Electron/client checks as UX gates, not strong protection.
• Prefer signed entitlements + server-side activation counting.
• Add offline grace period after successful activation.

Goal for v1.5.0:
Implement the foundation for open-core Pro licensing:

• client-side entitlement model
• feature gates
• signed license validation
• activation limit concept
• server-ready architecture

Server can be hosted on my own infrastructure if needed.