docs(api): publish canonical endpoint matrix, remove dead API hosts

[moshemalawach]

Implements backlog item P0-02: canonical API endpoint matrix.

All endpoints were live-probed on 2026-06-10. Host verdicts:

• api.aleph.cloud — DNS does not resolve. Removed as documented base URL.
• api1.aleph.cloud — TLS broken. Removed as dev/testing endpoint.
• api1.aleph.im — returns 404 on everything. Replaced in SDK examples.

Changes:

• docs/devhub/api/rest.md: base URLs replaced with working hosts (https://api.aleph.im primary, https://official.aleph.cloud alternative); added a canonical endpoint matrix covering CCN API, mirrors, VM scheduler, status, and credit API; added a curl https://api.aleph.im/api/v0/info/public.json quick check.
• docs/devhub/sdks-and-tools/python-sdk/index.md: api_server examples now use https://api.aleph.im.
• docs/nodes/resources/management/monitoring/index.md: fixed mismatched link (text said official.aleph.cloud/metrics, URL pointed to api.aleph.im/metrics) — now consistently official.aleph.cloud.
• docs/devhub/sdks-and-tools/aleph-cli/commands/message.md: aleph message sync examples now use https://api.aleph.im / https://api2.aleph.im instead of dead *.aleph.cloud hosts.

[foxpatch-aleph]

The PR correctly updates API, monitoring, and SDK documentation to use the new canonical endpoint api.aleph.im and removes references to the deprecated api1.aleph.cloud host. All changes are straightforward and accurate. A minor suggestion is to update a comment in the monitoring doc to match the new URL.

docs/nodes/resources/management/monitoring/index.md (line 29): The URL in the inline comment still says api.aleph.cloud/metrics but the actual link above now correctly points to https://official.aleph.cloud/metrics. Either remove the comment or update it to match the new URL.