feat(mcp): issue upload tickets for ingest

Add short-lived single-use HTTP upload tickets that authenticated MCP clients can request before uploading files to /mcp-ingest/uploads. This lets remote agents use curl without needing to read or expose the main MCP bearer token, avoiding oversized base64 tool arguments for larger files.

The upload endpoint now accepts either the normal bearer token or X-Obsidian-Wiki-Upload-Token. Ticket defaults can carry project, doc_type_hint, note, start_job, and file-count limits while uploads still stage outside the vault.

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

README.md

@@ -401,15 +401,16 @@ After `ingest` is enabled once, later `bash scripts/mcp_service.sh start` preser
 This adds write-capable MCP tools to the same `wiki-file-assets` server and bearer token. The server is tool-first: some MCP clients may show empty `resources` or `prompts` lists until a concrete `asset://source/sha256/...` URI is returned by `get_file_asset_metadata`, so use the tool list as the source of truth.
 
 - `get_ingest_upload_instructions` — returns the preferred upload methods, HTTP endpoint path, fields, limits, and curl example for remote agents.
+- `create_ingest_upload_ticket` — returns a short-lived, single-use upload token for the HTTP endpoint so remote agents can upload with curl without reading the main MCP bearer token.
 - `ingest_file_base64` — uploads one complete base64 file and optionally starts the local OpenCode ingest job; useful for small files or MCP clients that cannot make multipart HTTP requests.
 - `check_ingest_opencode_readiness` — verifies the local OpenCode binary, required run flags, project ingest skills, and optionally runs a no-write smoke test that confirms `wiki-ingest` can be loaded.
 - `start_ingest_job` — queues a local `opencode run --auto --format json` job with a fixed `/wiki-ingest` prompt for the completed uploads.
 - `get_ingest_job_status`, `get_ingest_job_result`, `cancel_ingest_job` — inspect or cancel the local job.
 
-For binary files, use the HTTP upload endpoint:
+For binary files, use the HTTP upload endpoint. If the remote agent cannot read the main MCP bearer token, first call `create_ingest_upload_ticket`, then upload with the returned token:
 
 ```bash
-curl -H "Authorization: Bearer <long-random-token>" \
+curl -H "X-Obsidian-Wiki-Upload-Token: <upload-token>" \
   -F "files=@drawing.pdf" \
   -F "project=bjd" \
   -F "doc_type_hint=drawing" \
@@ -417,7 +418,7 @@ curl -H "Authorization: Bearer <long-random-token>" \
   http://127.0.0.1:8765/mcp-ingest/uploads
 ```
 
-The endpoint accepts repeated `files` fields plus optional `project`, `doc_type_hint`, `note`, and `start_job` fields. It uses the same bearer token as `/mcp`; there is no second token to manage. For MCP clients that cannot make HTTP multipart requests, use `ingest_file_base64` for small files.
+The endpoint accepts repeated `files` fields plus optional `project`, `doc_type_hint`, `note`, and `start_job` fields. It accepts either the same bearer token as `/mcp` or the single-use upload ticket header. For MCP clients that cannot make HTTP multipart requests, `ingest_file_base64` remains available for small files, but large base64 arguments are fragile in many agent tool-call implementations.
 
 Run `check_ingest_opencode_readiness` before the first remote upload. Use `run_smoke_test: true` when you want OpenCode itself to prove it can load the project `wiki-ingest` skill; otherwise the static preflight is also run automatically before every `start_ingest_job`.