Add hook config write API

[abhinav-oai]

Why

After hooks/list exposes the hook inventory, clients need a follow-up control surface that can persist user choices for hooks

What

• Adds hooks/config/write for user-level hook enablement changes.
• Extends hooks/list entries with the current selector key and effective enabled state so clients can render toggles.
• Persists user overrides under [[hooks.config]] and filters disabled non-managed hooks out of runtime execution.
• Keeps managed hooks effectively enabled even when user config contains a matching disable entry.
• Leaves the current positional selector shape in place for now, with an inline TODO to replace it with a durable hook id later.

Verification

• Added hook-runtime coverage proving user config disables non-managed hooks but not managed hooks.
• Added config edit coverage for writing and removing hook config entries.
• Added an app-server integration test covering hooks/config/write and re-listing a disabled hook.

Stack

• Stacked on Add hooks/list app-server RPC #19778.

[chatgpt-codex-connector]

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[chatgpt-codex-connector]

Use durable hook IDs instead of positional key indices

Hook keys are persisted and later used for enable/disable, but the key is derived from group_index/handler_index. Reordering or inserting hooks in the source file changes indices, so an existing [[hooks.config]] entry can target a different hook (or none) on the next load. This can silently disable/enable the wrong command after config/plugin updates.

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