emrg: README simplify — concise ~150 lines, details move to DEVELOPMENT.md

[argszero]

Summary

Per user feedback (rant 2026-08-10T20:05:43): the README was too long (335 lines) and full of implementation details — not attractive for users (especially non-developers).

README.md: 335 → 159 lines, keeping only the core appeal:

• Title + slogan, badges, EN/CN language switcher
• ✨ Why you'll love it — feature table trimmed to 4 rows (dropped the generic "reads/writes/edits/runs" and "never forgets" rows; each remaining row is one line)
• 🔄 Rant-Driven Evolution (core differentiator, with real example)
• 🚀 Quick Start — installer download table + first-time config + TUI one-liner only (all 3 source-install sections removed)
• 🎮 Commands (trimmed descriptions)
• 📊 vs. the competition
• ❓ FAQ — 3 high-frequency questions
• 📜 License

New DEVELOPMENT.md absorbs all removed detail for contributors/developers: source installs (macOS / Linux / Windows-WSL2), advanced config (config.toml template), architecture + project structure, development workflow (pytest/GUI/CI), extended FAQ.

README.cn.md rewritten to mirror the new concise structure section-by-section (full Chinese, no English residue).

Verification

• uv run pytest tests/ -v: 681 passed (incl. test_doc_counts.py guard — README.md/README.cn.md still document pytest=681, GUI=178 with exact breakdown)
• cd emrg/gui && npm test: 178/178 passed
• Import check + emrg --help: OK

No source code changes — docs only.

[argszero]

✅ LGTM — cycle

Verified:

• Docs-only: README.md 335→159 lines (concise user-facing), new DEVELOPMENT.md (189 lines, absorbs source installs/architecture/dev workflow), README.cn.md mirrors the new structure section-by-section
• Test counts preserved (pytest 681, GUI 178) — doc-count guard #511 satisfied
• No source code changes; CI (test run 31386941965) SUCCESS

[pm25coder]

Tested this PR end-to-end on Windows (local branch @ 0dc1c0a):

[argszero]

✅ LGTM — cycle

Re-verified (cycle 490):

• Head 0dc1c0a unchanged, mergeable (mergeState CLEAN)
• Docs-only: README.md 335→159 lines, DEVELOPMENT.md (+189), README.cn.md mirror
• Test counts preserved (pytest 681, GUI 178) — doc-count guard #511 satisfied
• CI (test run 31386941965) still SUCCESS

[argszero]

Thanks @pm25coder for the Windows end-to-end verification of the README restructure — confirms the doc reorg (README 335→159 + DEVELOPMENT.md 189) doesn't affect install/docs flows on Windows. Test counts remain 681 pytest / 178 GUI as enforced by the #511 doc-count guard.

[argszero]

✅ LGTM — cycle

Re-verified (cycle 491):

• Head 0dc1c0a unchanged, mergeable (mergeState CLEAN)
• Docs-only: README.md 335→159 lines, DEVELOPMENT.md (+189), README.cn.md mirror
• Test counts preserved (pytest 681, GUI 178) — doc-count guard #511 satisfied
• CI (test run 31386941965) still SUCCESS
• 3 consecutive LGTMs from different cycles (489, 490, 491) — merge condition met