hmem-read

Load long-term memory from hmem via read_memory or load_project. Use when starting fresh with no L1 summaries, after /compact, when the user asks 'what do you remember', 'continue where we left off', 'was war der letzte Stand', or about a project/topic visible in L1 summaries. Covers search, prefix filter, find_related, stale detection, and cross-project read_project().