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]>

apps/docs/content/apis/openidoauth/endpoints.mdx

@@ -15,6 +15,13 @@ This would give us `${CUSTOM_DOMAIN}/.well-known/openid-configuration`.
 
 **Link to spec.** [OpenID Connect Discovery 1.0 incorporating errata set 1](https://openid.net/specs/openid-connect-discovery-1_0.html)
 
+ZITADEL also serves instance-scoped association files for native passkeys (not part of OIDC discovery):
+
+- `${CUSTOM_DOMAIN}/.well-known/apple-app-site-association`
+- `${CUSTOM_DOMAIN}/.well-known/assetlinks.json`
+
+See [Native app links for passkeys](/guides/integrate/login/oidc/native-app-links).
+
 ## authorization_endpoint
 
 `${CUSTOM_DOMAIN}/oauth/v2/authorize`