Hooks improvements

[zikajk]

Enhance ECA's existing 4 hook types (preRequest, postRequest, preToolCall, postToolCall) with structured feedback, without breaking existing hook scripts.

Scope:

• JSON output parsing from hooks
• Feed stderr to LLM on exit code 2 (for preToolCall)
• Tool input modification via updatedInput field
• Backward compatible with existing plain-text hooks

Motivation

• This https://github.com/bhauman/clojure-mcp-light/tree/main/commands is a good example how to profit from those changes.
• TBD Subagents can also profit from this

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[zikajk]

@ericdallo Could you please update clients to not show Output or the Error when they are empty (to remove clutter)?

[ericdallo]

Yes, I think makes sense

[ericdallo]

Done @zikajk

[ericdallo]

Done in #225