test(fuzz): arbitrary bytes into the HTTP door and the upload path (P12)

P2 promised these two targets and never added them. `fuzz_http_mcp_request`
feeds a method, a path, headers (token present, absent, wrong, raw) and a
JSON-RPC body drawn from the real method and tool names into the in-process
router. Whatever arrives, the door answers: no token live for the book is
refused 4xx, never run (INVARIANT 8), and a live token never makes the door
fail (no 5xx on the MCP route). Whether a token is live is asked of the door
itself (`FuzzDoor::carries_a_token`), so a token smuggled in an extra header
is judged by the real rule rather than by the target's guess.

`fuzz_upload_put` declares a size and a hash and sends bytes: taken only
when both are exactly what was declared, from the token the grant names,
and only once (INVARIANT 9); a 200 for anything else is the bug.

Both join the weekly matrix in scheduled.yml; fuzz/Cargo.lock gains
ledger-mcp's dependency closure because the targets drive its router.

.github/workflows/scheduled.yml

@@ -33,7 +33,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        target: [fuzz_journal_line, fuzz_entry_validate, fuzz_op_sequence, fuzz_core_serde, fuzz_store_open, fuzz_store_replay, fuzz_settings_replay, fuzz_import_csv, fuzz_config_parse, fuzz_extract_pdf, fuzz_extract_xlsx]
+        target: [fuzz_journal_line, fuzz_entry_validate, fuzz_op_sequence, fuzz_core_serde, fuzz_store_open, fuzz_store_replay, fuzz_settings_replay, fuzz_import_csv, fuzz_config_parse, fuzz_extract_pdf, fuzz_extract_xlsx, fuzz_http_mcp_request, fuzz_upload_put]
     steps:
       - uses: actions/checkout@v4
       - uses: jdx/mise-action@v2