Three fixes for memory+profile isolation bugs:
1. memory_tool.py: Replace module-level MEMORY_DIR constant with
get_memory_dir() function that calls get_hermes_home() dynamically.
The old constant was cached at import time and could go stale if
HERMES_HOME changed after import. Internal MemoryStore methods now
call get_memory_dir() directly. MEMORY_DIR kept as backward-compat
alias.
2. profiles.py: profile create --clone now copies MEMORY.md and USER.md
from the source profile. These curated memory files are part of the
agent's identity (same as SOUL.md) and should carry over on clone.
3. holographic plugin: initialize() now expands $HERMES_HOME and
${HERMES_HOME} in the db_path config value, so users can write
'db_path: $HERMES_HOME/memory_store.db' and it resolves to the
active profile directory, not the default home.
Tests updated to mock get_memory_dir() alongside the legacy MEMORY_DIR.