feat: native app links for passkeys (#12580)

# Which Problems Are Solved

- Native iOS/Android passkeys need OS trust files on the ZITADEL domain;
without them, Associated Domains / App Links verification fails.
- Operators could not configure iOS Team ID + Bundle ID or Android
package name + SHA-256 fingerprints on OIDC apps.
- `/.well-known/apple-app-site-association` and
`/.well-known/assetlinks.json` were not served from application config.

# How the Problems Are Solved

- Add iOS/Android app-link fields on OIDC app create/update (Application
API v2 + Management), with validation.
- Persist and project those fields; query active app-link configs
instance-wide.
- Serve AASA (`webcredentials`) and Digital Asset Links
(`get_login_creds`) from well-known paths, with configurable
`Cache-Control` and fingerprint normalization at serve time.
- Console UI to edit the fields, with links to the well-known endpoints.
- Operator docs for configuration, endpoints, caching, and verification.

# Additional Changes

- Document on API fields that well-known responses may be HTTP-cached
and platform verifiers may delay propagation.
- Runtime config: `WellKnown.AppLinksCacheControlMaxAge` (default `5m`;
`0` → `no-store`).

# Additional Context

- Closes #12497
- Implemented and reviewed as stack:
  - #12531 API contract
  - #12532 storage wiring
  - #12536 well-known endpoints
  - #12537 console
  - #12547 docs

---------

Co-authored-by: Cursor <[email protected]>

cmd/start/start.go

@@ -85,6 +85,7 @@ import (
 	"github.com/zitadel/zitadel/internal/api/ui/console"
 	"github.com/zitadel/zitadel/internal/api/ui/console/path"
 	"github.com/zitadel/zitadel/internal/api/ui/login"
+	"github.com/zitadel/zitadel/internal/api/well_known"
 	auth_es "github.com/zitadel/zitadel/internal/auth/repository/eventsourcing"
 	"github.com/zitadel/zitadel/internal/authz"
 	authz_repo "github.com/zitadel/zitadel/internal/authz/repository"
@@ -657,6 +658,9 @@ func startAPIs(
 	}
 	apis.RegisterHandlerOnPrefix(robots_txt.HandlerPrefix, robotsTxtHandler)
 
+	// native app link well-known files (instance-scoped)
+	apis.RegisterHandlerPrefixes(instanceInterceptor.Handler(well_known.NewHandler(queries, config.WellKnown)), well_known.HandlerPrefixes...)
+
 	// TODO: Record openapi access logs?
 	openAPIHandler, err := openapi.Start()
 	if err != nil {