docs(cli): teach the .sock rule instead of the deprecated --port 0 Unix-socket spelling #1631

Summary

The --host/--port help text (in both binaries) and docs/python-client.md still teach the deprecated --port 0 Unix-socket spelling. The current rule is the .sock suffix on --host, and the old form emits a deprecation warning at runtime.

Background

All four flag doc-comments read:

/// Host address to bind to (or Unix socket path when --port 0)
/// Port number to listen on (0 = Unix socket mode using --host as socket path)

• src/main.rs:1172,1176
• src/bin/mlx_server.rs:403,407

Ground truth is in src/server/transport.rs: the selection rule is "--host ending in .sock is a Unix domain socket path, whatever --port says" (the b10621 rule, transport.rs:107), and the --port 0 form emits a deprecation warning (transport.rs:98,133-138). In docs, README.md:115 already uses the new spelling, but docs/python-client.md:61-62 still explains the old rule ("--port 0 reinterprets --host as the socket path") and :81 repeats it.

Proposed Solution

Rewrite the four doc-comments and the two python-client.md passages around the .sock rule, mentioning --port 0 only as a deprecated alias if at all.

Implementation Notes

• These are six one-line text edits with no logic change.

Acceptance Criteria

• --help for both binaries describes the .sock rule as primary.
• docs/python-client.md no longer teaches --port 0 as the rule.

Original Suggestion

Title: docs(cli): --host/--port help text still teaches the deprecated --port 0 Unix-socket spelling

The --host/--port help text (in both binaries) and docs/python-client.md still teach the deprecated --port 0 Unix-socket spelling. The current rule is the .sock suffix on --host, and the old form emits a deprecation warning at runtime.

Evidence

All four flag doc-comments read:

/// Host address to bind to (or Unix socket path when --port 0)
/// Port number to listen on (0 = Unix socket mode using --host as socket path)

• src/main.rs:1172,1176
• src/bin/mlx_server.rs:403,407

Ground truth: src/server/transport.rs:103-140 — rule 1 is "--host ending in .sock is a Unix domain socket path, whatever --port says. This is the b10621 rule and the spelling to use", and the --port 0 form emits a deprecation warning (transport.rs:133-138).

Docs: README.md:115 already uses the new spelling, but docs/python-client.md:61-62 still explains the old rule ("--port 0 reinterprets --host as the socket path") and :81 repeats it.

Suggested fix

Rewrite the four doc-comments and the two python-client.md passages around the .sock rule, mentioning --port 0 only as a deprecated alias if at all. Six one-line text edits.

Acceptance criteria

• --help for both binaries describes the .sock rule as primary
• docs/python-client.md no longer teaches --port 0 as the rule