feat(mcp): add simplified ingest uploads

Add a one-shot IngestManager upload path, an ingest_file_base64 MCP tool, and an authenticated /mcp-ingest/uploads multipart HTTP endpoint so remote agents can transfer files without manual chunk orchestration.

Keep uploaded files in runtime staging outside the vault and let wiki-ingest/OpenCode decide archival, registry updates, and index rebuilds.

Update service output, docs, and agent rules to make the preferred upload path discoverable while preserving chunked tools as a fallback.

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

.env.example

@@ -56,6 +56,9 @@ OBSIDIAN_MCP_ENABLED_TOOLS=file-assets
 # After enabling, call the MCP tool `check_ingest_opencode_readiness` before
 # the first upload; set run_smoke_test=true to verify OpenCode can load the
 # project wiki-ingest skill without editing files.
+# Preferred remote file upload path: POST multipart/form-data to
+# /mcp-ingest/uploads with the same Authorization bearer token as /mcp. Agents
+# can also call `get_ingest_upload_instructions` for exact fields/examples.
 # Keep this runtime root outside OBSIDIAN_VAULT_PATH; uploads are staging inputs,
 # and wiki-ingest decides how sources are archived into the vault.
 # Prefer OBSIDIAN_MCP_ENABLED_TOOLS=file-assets,ingest for new configs. This