rename project to MultiforaDB

Prose and benchmark tables use MultiforaDB; the binary, the CLI usage
line, the log-message prefix and the default database file use
multiforadb.

Two consequences worth noting:

- build.zig.zon's fingerprint is derived from the package name, so it
  had to change with it (Zig refuses to build otherwise). A consumer
  pinning this package by fingerprint needs updating.
- the default --db path is now multiforadb.log, and getCmdLineOpts
  reports it as dbpath. An existing mongo-lite.log has to be passed
  explicitly with --db.

The e2e harness abbreviated the old name as ML_; that is now MFDB_,
including the documented ML_BIN override (MFDB_BIN) and the scratch
file names. MD_ (mongod) is untouched.

compare-run.sh spawned the server by absolute path under a
sandbox/mongo-lite directory that no longer exists; that block already
runs from tests/e2e, so it uses a relative path now.

The archived reports under tests/e2e/results/ keep the old name: they
record what the old binary measured.

tests/e2e/e2e6.js

@@ -1,6 +1,6 @@
 // E2E part 6: the full lifecycle, self-contained.
 //
-// Spawns its own mongo-lite server on a fresh log file and drives the whole
+// Spawns its own multiforadb server on a fresh log file and drives the whole
 // feature surface through the official driver: CRUD + query operators +
 // aggregation + error codes + secondary indexes + TTL expiry + admin
 // commands, then restarts the server twice — once gracefully, once with
@@ -12,7 +12,7 @@
 //   node tests/e2e/e2e6.js
 //
 // Env:  E2E6_PORT  listen port (default 27220)
-//       ML_BIN     server binary (default ../../zig-out/bin/mongo-lite)
+//       MFDB_BIN     server binary (default ../../zig-out/bin/multiforadb)
 //       E2E6_KEEP  keep the log file after the run
 const { MongoClient, ObjectId } = require('mongodb');
 const { spawn } = require('child_process');
@@ -20,7 +20,7 @@ const fs = require('fs');
 const path = require('path');
 
 const PORT = Number(process.env.E2E6_PORT || 27220);
-const BIN = process.env.ML_BIN || path.resolve(__dirname, '../../zig-out/bin/mongo-lite');
+const BIN = process.env.MFDB_BIN || path.resolve(__dirname, '../../zig-out/bin/multiforadb');
 const DBFILE = process.env.E2E6_DB || path.resolve(__dirname, '../../.zig-cache/e2e6-full.log');
 const URL = `mongodb://127.0.0.1:${PORT}`;