feat: enforce functional verification, mandatory quality pipeline, and requirement checks

Add three new sections to AGENTS.md addressing workflow gaps observed in
a session where 6 features were implemented but none were functionally
tested — only static analysis (type checks, linting) was used, resulting
in broken features shipped as 'done'.

New rules:
- Functional Verification: features must be end-to-end tested before
  completion; static analysis alone is explicitly insufficient
- Mandatory Quality Pipeline: every feature gets reviewer + tester passes;
  no batch validation; quality over quantity under time pressure
- Requirement Understanding Verification: verify understanding before
  implementing features with implicit expectations or domain concepts

Also simplifies tester bash permissions and adds plan write permission.

.config/opencode/agents/tester.md

@@ -6,26 +6,15 @@ temperature: 0.1
 permission:
   edit: allow
   bash:
-    "uv run pytest*": allow
-    "uv run python -m pytest*": allow
-    "pytest*": allow
-    "python -m pytest*": allow
-    "npm test*": allow
-    "npm run test*": allow
-    "pnpm test*": allow
-    "pnpm run test*": allow
-    "bun test*": allow
-    "npm run dev*": allow
-    "npm start*": allow
-    "npx jest*": allow
-    "npx vitest*": allow
-    "npx playwright*": allow
+    "*": deny
+    "uv *": allow
+    "bun *": allow
     "go test*": allow
+    "docker *": allow
     "cargo test*": allow
     "make test*": allow
     "gh run*": allow
     "gh pr*": allow
-    "*": deny
 ---
 
 You are the Tester subagent.