fix: remove eager wildcard imports from __init__.py files

tools/__init__.py was importing github_tool (which needs gitpython)
even in tests that only needed file_scanner. agents/__init__.py had
the same problem pulling the entire dep graph on any agent import.
Callers now import directly from the submodule they need.

app/agents/__init__.py

@@ -1,7 +0,0 @@
-from app.agents import (
-    repo_analysis_agent as repo_analysis_agent,
-    bug_detection_agent as bug_detection_agent,
-    test_generation_agent as test_generation_agent,
-    code_review_agent as code_review_agent,
-    report_generator_agent as report_generator_agent
-)

app/tools/__init__.py

@@ -1,5 +0,0 @@
-from app.tools.github_tool import clone_repository as clone_repository, delete_repository as delete_repository
-from app.tools.file_scanner import scan_repository as scan_repository, get_entry_points as get_entry_points, get_python_files as get_python_files
-from app.tools.ast_parser import parse_python_file as parse_python_file, parse_repository as parse_repository
-from app.tools.pytest_runner import run_tests as run_tests
-from app.tools.static_analyzer import run_full_analysis as run_full_analysis