feat(conduit): Add conduit auth functions

[IanWoodard]

Adds backend helpers for generating Conduit authentication credentials. Conduit is Sentry's real-time delivery platform that enables scalable streaming from backend services to frontend clients.

This PR provides the foundational utilities needed for API endpoints to generate Conduit credentials (JWT tokens and channel IDs) that the conduit-client will use to establish streaming connections.

Changes

• New utilities in src/sentry/conduit/auth.py

  • generate_channel_id(): UUID4 generation for stream identifiers
  • generate_conduit_token(): RS256 signed JWT with org_id, channel_id, and 10 minute expiration
  • get_conduit_credentials(): Returns {url, token, channel_id} dict for the client

• Configuration src/sentry/conf/server.py

  • CONDUIT_PRIVATE_KEY (required): RSA private key for JWT signing
  • CONDUIT_GATEWAY_URL: Gateway base URL
  • CONDUIT_JWT_ISSUER / CONDUIT_JWT_AUDIENCE: JWT claims

Note: Requires CONDUIT_PRIVATE_KEY environment variable to be set before use.

[linear]

INFRENG-97 Create helper functions for generating tokens and channel ids

[codecov]

Codecov Report

❌ Patch coverage is 97.22222% with 1 line in your changes missing coverage. Please review.
✅ All tests successful. No failed tests found.

Files with missing lines	Patch %	Lines
src/sentry/conf/server.py	75.00%	1 Missing ⚠️

Additional details and impacted files

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- Misses      73268     73307      +39     
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