Add versioning, update tool, and soft-delete

Schema: public_id + version columns with UNIQUE constraint,
delete_timestamp for soft-delete.

Tools: store_flashcard accepts optional public_id, update_flashcard
creates a new version preserving history, delete_flashcard inserts
a tombstone row and removes the Qdrant point.

Qdrant: point ID is public_id (only latest version indexed).

README.md

@@ -1,12 +1,12 @@
-# St-Pierre - Knowledge MCP Server
+# St-Pierre - Flashcard MCP Server
 
-Remote MCP server that stores and retrieves knowledge using Qdrant vector
+Remote MCP server that stores and retrieves flashcards using Qdrant vector
 database and OpenAI embeddings.
 
 ## Tools
 
-### `store_knowledge`
-Store a piece of knowledge for later retrieval. Automatically generates
+### `store_flashcard`
+Store a flashcard for later retrieval. Automatically generates
 embeddings via OpenAI and persists them in Qdrant.
 
 Parameters:
@@ -17,8 +17,8 @@ Parameters:
 - `user` (string, optional): User identifier
 - `context` (string, optional): What triggered this
 
-### `search_knowledge`
-Semantic search across stored knowledge.
+### `search_flashcard`
+Semantic search across stored flashcards.
 
 Parameters:
 - `query` (string, required): Search query
@@ -106,7 +106,7 @@ Add to your MCP client config:
 ```json
 {
   "mcpServers": {
-    "knowledge": {
+    "flashcard": {
       "url": "http://your-server:8080/mcp",
       "headers": {
         "Authorization": "Bearer my-secret-token"