Add missing __init__.py files for 5 packages

[admin-init]

Problem

Five packages under src/uni_dev/ are missing __init__.py files:

• core/
• agents/
• security/
• store/
• tui/

They work as implicit namespace packages, but this is inconsistent with middleware/, monitoring/, and webhooks/ which all have __init__.py with proper exports.

Required Changes

Add __init__.py with appropriate exports:

Package	Should Export
core/	PipelineState, compile_pipeline, gate functions
agents/	All 5 create_* factory functions
security/	LogFilter
store/	IssueStore
tui/	(empty or minimal — internal package)

Files to Create

• src/uni_dev/core/__init__.py
• src/uni_dev/agents/__init__.py
• src/uni_dev/security/__init__.py
• src/uni_dev/store/__init__.py
• src/uni_dev/tui/__init__.py

Acceptance Criteria

• All 5 packages have __init__.py
• Public APIs are exported with __all__
• from uni_dev.security import LogFilter works
• from uni_dev.store import IssueStore works
• pytest passes
• uvx ruff check src/ passes

[admin-init]

Closed by PR #29 - Added init.py to core, agents, security, store, tui packages