feat: markdown memory system — Hope learns from conversations

- agent/memory_mcp.py: MCP server with memory_recall, memory_save, memory_list
  tools backed by .md files in /memory (simple keyword matching for v1)
- memory/ dir bind-mounted into container, persists across rebuilds,
  easily backed up via git
- System prompt instructs Hope to recall on past references and save
  personal info/preferences naturally without announcing it
- Dockerfile: copy memory_mcp.py; compose: ./memory:/memory volume

agent/agent.py

@@ -38,6 +38,7 @@ GEMMA_MODEL = os.environ.get("GEMMA_MODEL", "gemma-4-e4b")
 GEMMA_API_KEY = os.environ.get("GEMMA_API_KEY", "not-needed")
 WEB_MCP_ENABLED = os.environ.get("WEB_MCP_ENABLED", "true").lower() in ("1", "true", "yes")
 FIRECRAWL_BASE = os.environ.get("FIRECRAWL_BASE", "http://192.168.86.2:3002")
+MEMORY_DIR = os.environ.get("MEMORY_DIR", "/memory")
 
 SYSTEM_PROMPT = textwrap.dedent("""\
     You are Hope, a warm, conversational voice assistant. You are talking TO
@@ -76,6 +77,20 @@ SYSTEM_PROMPT = textwrap.dedent("""\
     short summary — relay it naturally in your own words.
     Use get_time when the user asks what time or day it is. If they mention
     a city, pass it as the location argument.
+
+    # Memory
+    You have persistent memory across conversations, stored as notes you can
+    search and add to.
+    - Use memory_recall at the start of a conversation, or whenever the user
+      references past information ("what did I tell you about...", "remember
+      when..."). Weave what you find in naturally.
+    - Use memory_save when the user shares personal information, preferences,
+      or important facts worth remembering: names, birthdays, preferences,
+      projects, anything they'd expect you to know later. Pick a short topic
+      name for each thing you save.
+    - Be natural about it. Never announce "I'm saving that to memory" — just
+      remember it and move on. If a recall comes up empty, don't mention the
+      search; just answer as if you'd never heard it before.
 """)
 
 
@@ -200,6 +215,20 @@ def build_mcp_toolsets() -> list[mcp.MCPToolset]:
     )
     logger.info("Weather MCP toolset enabled (wttr.in)")
 
+    memory_mcp_script = os.path.join(os.path.dirname(os.path.abspath(__file__)), "memory_mcp.py")
+    toolsets.append(
+        mcp.MCPToolset(
+            id="memory",
+            mcp_server=mcp.MCPServerStdio(
+                command=python_bin,
+                args=[memory_mcp_script],
+                env={**os.environ, "MEMORY_DIR": "/memory"},
+                client_session_timeout_seconds=30,
+            ),
+        )
+    )
+    logger.info("Memory MCP toolset enabled (%s)", MEMORY_DIR)
+
     extra = os.environ.get("EXTRA_MCP_SERVERS", "")
     if extra:
         try: