fix(mcp): remove base64 ingest tool

Remove ingest_file_base64 from the ingest MCP tool surface so remote agents use the upload-ticket HTTP multipart path instead of oversized JSON/base64 tool arguments.

Update docs and agent rules to make base64 upload explicitly unsupported as an MCP tool while preserving ticket-based uploads outside the vault.

Validation: python3 -m unittest discover -v; python3 -m py_compile obsidian_wiki/mcp_server.py tests/test_mcp_server_remote.py; git diff --check

tests/test_mcp_server_remote.py

@@ -1,5 +1,4 @@
 import asyncio
-import base64
 import hashlib
 import json
 import os
@@ -354,7 +353,7 @@ class RemoteMcpServerTests(unittest.TestCase):
         self.assertIn("check_ingest_opencode_readiness", FakeMCP.tool_names)
         self.assertIn("get_ingest_upload_instructions", FakeMCP.tool_names)
         self.assertIn("create_ingest_upload_ticket", FakeMCP.tool_names)
-        self.assertIn("ingest_file_base64", FakeMCP.tool_names)
+        self.assertNotIn("ingest_file_base64", FakeMCP.tool_names)
 
     def test_create_ingest_upload_ticket_tool_returns_http_only_token(self):
         class FakeMCP:
@@ -407,57 +406,6 @@ class RemoteMcpServerTests(unittest.TestCase):
         self.assertEqual(ticket["max_files"], 1)
         self.assertFalse(ticket["start_job"])
 
-    def test_ingest_file_base64_tool_uploads_without_chunking(self):
-        class FakeMCP:
-            tools = {}
-
-            def __init__(self, _name, **_kwargs):
-                pass
-
-            def tool(self):
-                def decorator(func):
-                    self.tools[func.__name__] = func
-                    return func
-
-                return decorator
-
-            def resource(self, *_args, **_kwargs):
-                def decorator(func):
-                    return func
-
-                return decorator
-
-            def prompt(self, *_args, **_kwargs):
-                def decorator(func):
-                    return func
-
-                return decorator
-
-        with (
-            tempfile.TemporaryDirectory() as tmp,
-            patch.dict("sys.modules", {"mcp.server.fastmcp": type("Mod", (), {"FastMCP": FakeMCP})()}),
-        ):
-            root = Path(tmp)
-            mcp_server.create_server(
-                vault_path=root / "vault",
-                enable_ingest=True,
-                project_root=root / "project",
-                ingest_runtime_root=root / "runtime",
-            )
-            payload = b"one shot upload"
-            result = FakeMCP.tools["ingest_file_base64"](
-                file_name="source.pdf",
-                data_base64=base64.b64encode(payload).decode("ascii"),
-                project="bjd",
-                doc_type_hint="drawing",
-                start_job=False,
-            )
-
-        self.assertEqual(result["job"], None)
-        self.assertEqual(result["upload"]["state"], "complete")
-        self.assertEqual(result["upload"]["file_name"], "source.pdf")
-        self.assertEqual(result["upload"]["sha256"], "sha256:" + hashlib.sha256(payload).hexdigest())
-
     def test_create_server_can_disable_file_asset_tools(self):
         class FakeMCP:
             tool_names = []