docs(changelog): curate 0.4.1 release + tighten changelog

[gandarfh]

Summary

Prepares CHANGELOG.md for the v0.4.1 release and tightens the whole changelog.

Two commits:

1. Cuts the ## [0.4.1] section from the work merged into main since v0.4.0 — step 1 of docs/RELEASE.md, required by the pipeline's validate job.
2. Rewrites the ## [0.4.0] section — one line per item, single language (EN), no implementation detail, no duplicates.

The file went from 398 → 85 lines.

0.4.1 — maintenance release

• Added — one-line curl | sh installer.
• Changed — self-hosted / offline fonts (no Google Fonts CDN).
• Fixed — editor focus listeners, HTTP block flash on blur, silent save failures in Connections.

0.4.0 — cleanup

• Multi-paragraph items (4–7 lines each) → one line per item.
• Mixed PT/EN → all EN (consistent with the OSS docs and the 0.4.1 section).
• Duplicates removed: DocHeader appeared twice ("card above CM6" + "Inline DocHeader"); "Pre-flight Run-all gate" in Added contradicted "Run all button removed" in Removed; TipTap appeared in both Changed and Removed.
• Implementation detail that doesn't belong in a user-facing changelog removed (Tauri command names, Rust structs, internal refactors, quality gates, monorepo reorg).

Out of scope

• Landing-page fixes (fix(web)), docs, chore, test — internal, not release-changelog material.
• The TUI standard mode lives on feat/tui-input-model (not yet on main) — it ships in a future release.

Next step

After merge: git tag v0.4.1 && git push origin v0.4.1 on main triggers the release pipeline.

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