chore: update Dockerfile and tests for BASIC_MEMORY_PROJECT_ROOT

Updates containerized deployment to use both environment variables
for clean project organization and path constraints.

## Dockerfile Changes

- Set BASIC_MEMORY_HOME=/app/data/basic-memory (main project location)
- Set BASIC_MEMORY_PROJECT_ROOT=/app/data (constrain all projects to volume)
- Create /app/data/basic-memory directory

Benefits:
- Main project cleanly separated in /app/data/basic-memory/
- All projects constrained to /app/data/ (volume mount)
- Users can't accidentally create projects outside mounted volume
- Consistent with cloud deployment pattern

Directory structure:
/app/data/
  ├── basic-memory/  (main project)
  │   └── *.md
  └── other-project/ (optional additional projects)

## Test Fixture Changes

- Add config cache invalidation in config_manager fixture
- Ensures each test starts with clean config state
- Prevents test pollution from cached config values

Signed-off-by: phernandez <paul@basicmachines.co>

Author: phernandez

Dockerfile

@@ -24,11 +24,12 @@ WORKDIR /app
 RUN uv sync --locked
 
 # Create necessary directories and set ownership
-RUN mkdir -p /app/data /app/.basic-memory && \
+RUN mkdir -p /app/data/basic-memory /app/.basic-memory && \
     chown -R appuser:${GID} /app
 
 # Set default data directory and add venv to PATH
-ENV BASIC_MEMORY_HOME=/app/data \
+ENV BASIC_MEMORY_HOME=/app/data/basic-memory \
+    BASIC_MEMORY_PROJECT_ROOT=/app/data \
     PATH="/app/.venv/bin:$PATH"
 
 # Switch to the non-root user

tests/conftest.py

@@ -78,6 +78,11 @@ def app_config(config_home, tmp_path, monkeypatch) -> BasicMemoryConfig:
 def config_manager(
     app_config: BasicMemoryConfig, project_config: ProjectConfig, config_home: Path, monkeypatch
 ) -> ConfigManager:
+    # Invalidate config cache to ensure clean state for each test
+    from basic_memory import config as config_module
+
+    config_module._CONFIG_CACHE = None
+
     # Create a new ConfigManager that uses the test home directory
     config_manager = ConfigManager()
     # Update its paths to use the test directory