h0x91b/dev-3.0/25

Moved the testing detail out of AGENTS.md into a new repo-local /verify-changes skill (which vitest config covers what, what a change needs covered, house style, mocking Electrobun RPC and useT(), reproducing flakes under load, coverage expectations), leaving the two verification gates and the browser-QA mandate inline where they cannot be missed. The 1-5 tip coolness rubric now lives on a TipScore union type in src/mainview/tips.ts instead of being restated in prose, and the key-files list gained the entries an agent is most likely to overlook: shared types, the RPC handler barrel, the reducer, design tokens, the keymap, shipped skill text, CLI exit codes, CI workflows, and the decision records.