feat: add compression time to /dcp stats

[spoons-and-mirrors]

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[chatgpt-codex-connector]

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[Copilot]

Pull request overview

Adds tracking and reporting of how long it takes the LLM to generate compress tool inputs, and surfaces that metric in /dcp stats.

Changes:

• Track per-compress tool-call “pending → running” duration and accumulate it into session stats.
• Persist and reset the new compressionTimeMs stat, and add a compressionStarts map to session state.
• Display the new metric in /dcp stats and add tests for the event hook behavior.

Reviewed changes

Copilot reviewed 8 out of 8 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
tests/hooks-permission.test.ts	Adds tests validating event-hook timing accumulation and filtering to compress only.
lib/state/types.ts	Extends session state/types with compressionTimeMs and compressionStarts.
lib/state/state.ts	Initializes, resets, and loads the new session stat and map.
lib/hooks.ts	Adds createEventHandler that records compress input-generation durations from events.
lib/compress/range.ts	Removes an extraneous stray character/line in the tool implementation.
lib/compress/message.ts	Removes an extraneous stray character/line in the tool implementation.
lib/commands/stats.ts	Prints the new compression/summary time metric in /dcp stats.
index.ts	Registers the new event hook handler.

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