chore(release): cut v0.4.1

[attila]

Summary

Cuts v0.4.1. Bumps Cargo.toml 0.4.0 → 0.4.1, rotates the [Unreleased] CHANGELOG block into a dated section, and updates the README install snippet's VERSION constant to point at the new release.

Headline change in this release (curated in CHANGELOG.md):

• Fix: SessionStart hook output now reaches the model as hookSpecificOutput.additionalContext instead of the terminal-only systemMessage chip, so the pinned-conventions index and meta-instruction actually seed the conversation on session start (fix: deliver SessionStart hook payload to model context; silence PostCompact #65).
• Change: PostCompact no longer emits a hook payload. Claude Code's hook output validator rejects hookSpecificOutput for this event, leaving only the chip-only systemMessage envelope — which never reaches the model and renders as long terminal noise on every /compact. The handler now does its dedup-file truncation silently; on-demand pattern injection via PreToolUse continues to work (fix: deliver SessionStart hook payload to model context; silence PostCompact #65).

No breaking changes to the binary or hook protocol. The HookOutput Rust type was reshaped internally; lore has no documented Rust library consumers.

Background and limitation context:

• docs/hook-pipeline-reference.md — per-event envelope table and the PostCompact known-limitation note.
• ROADMAP.md — candidate workarounds for restoring a post-compaction re-prime channel.
• docs/solutions/integration-issues/verify-host-delivery-not-just-hook-exit-2026-05-22.md — institutional learning from the investigation.

See docs/release-process.md for the full runbook.

Test plan

• just ci clean locally (release-prep runs it before printing the next-steps banner)
• Behavioural verification on the headline fix was completed during fix: deliver SessionStart hook payload to model context; silence PostCompact #65's review cycle: SessionStart payload reaches the model on startup/resume/clear/compact; /compact no longer raises a validator error and produces no terminal chip; PreToolUse continues to inject on demand.