Rename Project Memory to Workspace Memory

Rename all references from "Project Memory" to "Workspace Memory" to avoid
future conflation if a "project" concept is introduced later.

Changes:
- Rename read_project_memory() -> read_workspace_memory()
- Update all prompts, tool descriptions, and comments
- Update header parsing in memory.rs to use "# Workspace Memory"
- Update display detection for "=== Workspace Memory ==="
- Update documentation and analysis/memory.md

11 files changed, ~36 occurrences updated.

docs/tools.md

@@ -292,7 +292,7 @@ Perform web-based research on a topic.
 
 ### remember
 
-Save discoveries to project memory.
+Save discoveries to workspace memory.
 
 **Parameters**:
 - `notes` (string, required): Markdown-formatted notes to add to memory