docs: split README and living design doc

[bobthearsonist]

Closes #4

Summary

• Rework the top-level README into a product, architecture, setup, privacy, and development overview.
• Replace the long design document with future-facing living design notes, known limitations, and open decisions.
• Update plugin docs and the scaffolded skill to point at the new README/design split.

Validation

• git diff --check
• local markdown link check across updated docs

[bobthearsonist]

@copilot review

[Copilot]

@copilot review

Code review

All relative links resolve correctly across all five changed files. No broken cross-references. Overall the restructuring is clean and achieves the stated goal of issue #4.

✅ What's good

• README.md reading flow is logical (intro → why → what → visual → pieces → arch → setup → commands → privacy → dev). The Mermaid flowchart is a solid replacement for the old ASCII art.
• docs/design.md trimmed from 1,185 to 239 lines with only future-facing content remaining. Design principles, known limitations, and open decisions table are valuable for contributors.
• SVG asset has proper accessibility attributes (role="img", aria-labelledby, <title>, <desc>).
• All plugin READMEs and SKILL.md correctly cross-reference the new README/design split.

⚠️ Minor items to consider

1. stroke-dasharray format in the Mermaid classDef (README.md line 34): stroke-dasharray: 5 5 uses a space-separated value. GitHub's renderer handles it, but stroke-dasharray: 5,5 (comma) is more broadly compatible with older Mermaid versions if that matters.

2. Personal note names in the SVG (docs/assets/obsidian-note-preview.svg): "Daily ADHD Brain Log" / "0 Daily ADHD Brain Logs" is authentic context but exposes personal workflow details in a public repo. A more neutral example like "Daily Notes / 20260502.md" would be safer for a general-audience repo. This is a judgment call.

3. Issue Separate README from living design document #4 self-link in README (README.md line 241): Linking to the issue that this PR closes in the "Deeper docs and planning" section will stay around after merge. Consider removing it from the permanent README and keeping it only in the PR description/commit message.

No blocking issues. LGTM with those minor suggestions as optional follow-ups.

[bobthearsonist]

Addressed Copilot feedback: Mermaid dasharray now uses 5,5; SVG preview uses neutral Daily Notes examples; removed the permanent issue #4 self-link. Validation: README local links OK (11 checked), SVG XML parses OK, and rsvg-convert rendered the SVG to a 1280x820 PNG successfully.

[bobthearsonist]

@copilot review

[Copilot]

@copilot review

Code review (second pass)

All three feedback items from the first review are applied correctly:

• stroke-dasharray: 5,5 — confirmed on README.md line 34.
• SVG neutral examples — "Daily ADHD Brain Log" / "0 Daily ADHD Brain Logs" are gone; "Daily Notes" used throughout SVG.
• Issue Separate README from living design document #4 self-link removed — no longer in README.md's "Deeper docs and planning" section.

Validation passes:

• 27/27 relative links across all five changed files resolve correctly (0 broken).
• SVG XML parses without errors.
• SVG retains role="img", aria-labelledby, <title>, and <desc> accessibility attributes.

No new issues found. LGTM — ready to merge.