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.