Restructure the README to improve readability

[kergoth]

Current state

The README is ~600 lines organized around setup mechanics and OS-split software lists. It reflects how the repository is structured rather than what using this environment actually looks like. Someone reading it to evaluate the setup has to extract that picture themselves.

Goal

Restructure the README as a curated environment tour: what this setup covers and how the pieces relate. Split the software inventory out into a supporting doc first, in its current form (the same way docs/as-needed.md works), so nothing is lost during the reorganization. The inventory's own form (matrix, platform consolidation, etc.) can be revisited as a follow-on.

Areas to cover in the tour, with screenshots where they add clarity (prompt, terminal, desktop integrations, agent tooling):

• shell, prompt, and terminal
• tmux
• Git, SSH, and development environment
• editors (Vim, Zed)
• Home Manager and package management approach
• agent tooling
• workflow infrastructure (Syncthing, ghq, containerized development)
• Obsidian and knowledge work
• OS configuration, especially macOS defaults and keyboard normalization
• pinned externals and the review-first update model
• installed software (referenced doc)

Suggested sequence

• Split the current software inventory to a new docs/installed.md (current form, no restructuring yet)
• Restructure the README around the tour areas above; consider kutsan/dotfiles as a structural reference for the tour content
• Add screenshots for visual subsystems (prompt, terminal, desktop integrations)
• Follow-on: revisit the inventory doc's form (cross-platform matrix, kutsan-style entries, etc.). Improve GUI application setup coverage for Linux and FreeBSD #65 uses a compatibility matrix and can serve as a reference point

[kergoth]

One more consideration: someone evaluating the setup will likely want to understand how it works, not just what it covers. The chezmoi layering, run script model, externals/lock flow, and templating approach are all non-obvious. That content is detailed enough to warrant its own doc rather than living in the tour — the README can link to it the same way it will link to the inventory.