fix: restore curated files to system memory

Files that should stay in system (always loaded):
- discord.md, discord_formatting_guide.md
- conversation_search_guide.md
- research_workflow.md, subagent_usage_guide.md

These are actively used, not archived.

Only archive to reference when truly inactive.

system/projects_index.md

@@ -18,10 +18,15 @@ limit: 3000
 - `project_paths.md` — Absolute paths reference
 - `lilith_clarification.md` — Two Liliths distinction (recent)
 
-**Active References:**
+**Active References (Curated):**
 - `matrix_formatting_reference.md` — Matrix color/chromatic syntax
 - `tools_reference.md` — Available tools
 - `matrix.md` — Matrix basics
+- `discord.md` — Discord integration
+- `discord_formatting_guide.md` — Discord formatting patterns
+- `conversation_search_guide.md` — Search patterns
+- `research_workflow.md` — Research process
+- `subagent_usage_guide.md` — Subagent patterns
 
 ---
 
@@ -73,20 +78,6 @@ These projects are currently in development. Files are in `system/` (always load
 
 These projects are archived. Files are in `reference/` (load when needed).
 
-### Discord & Matrix (Moved from System)
-**Status:** Stable patterns, reference use only
-**Files:**
-- `reference/discord.md` — General Discord info
-- `reference/discord_formatting_guide.md` — Formatting patterns
-- `reference/matrix_protocol.md` — Matrix technical details
-
-### Workflows & Guides (Moved from System)
-**Status:** Process documentation
-**Files:**
-- `reference/conversation_search_guide.md` — Search patterns
-- `reference/research_workflow.md` — Research process
-- `reference/subagent_usage_guide.md` — Subagent patterns
-
 ### Infrastructure History
 **Files:**
 - `reference/infrastructure_detailed.md`