Implement client Pause and Unpause command

[prateek-kumar-improving]

Summary

Implement CLIENT PAUSE and CLIENT UNPAUSE commands for both standalone and cluster clients. CLIENT PAUSE suspends all client commands for a specified timeout, and CLIENT UNPAUSE resumes processing.

Issue link

This Pull Request is linked to issue: #236

Features / Behaviour Changes

• Add ValkeyGlide::clientPause(int $timeout, ?string $mode = null): ValkeyGlide|bool|string
• Add ValkeyGlide::clientUnpause(): ValkeyGlide|bool|string
• Add ValkeyGlideCluster::clientPause(int $timeout, ?string $mode = null): ValkeyGlideCluster|bool|string
• Add ValkeyGlideCluster::clientUnpause(): ValkeyGlideCluster|bool|string
• With OPT_REPLY_LITERAL enabled, returns "OK" string
• Supports pause modes: "ALL" (default, blocks all commands) and "WRITE" (blocks only writes)
• In cluster mode, glide-core routes to all primary nodes by default (no explicit route param needed)

Implementation

• execute_client_pause_command() in valkey_glide_commands.c — takes timeout (long) + optional mode (string)
• execute_client_unpause_command() in valkey_glide_commands.c — zero-arg command
• CLIENT_PAUSE_METHOD_IMPL and CLIENT_UNPAUSE_METHOD_IMPL macros in valkey_glide_commands_common.h
• ClientPause uses prepare_message_args (handles long + optional string args)
• ClientUnpause uses prepare_zero_args
• Both use execute_and_handle_batch helper and status processors

Testing

Standalone tests (tests/ValkeyGlideTest.php) added.
Cluster tests (tests/ValkeyGlideClusterTest.php) added.
Build passes with -Werror, lint clean on all modified files.

Checklist

Before submitting the PR make sure the following are checked:

• This Pull Request is related to one issue.
• Commit message has a detailed description of what changed and why.
• Tests are added or updated.
• CHANGELOG.md and documentation files are updated.
• Destination branch is correct - main or release
• Create merge commit if merging release branch into main, squash otherwise.

[jamesx-improving]

Nice, clean reuse of the existing unified-command framework — the C-level implementation mirrors reset / bgSave and I have no correctness or security concerns there. Left a few unverified test-side questions inline that I couldn't confirm without an initialized glide-core submodule; happy to re-review once you've had a look.

[jamesx-improving]

LGTM, thanks for the fixes.