needsPackage should be able to load a package without its unadorned symbols

This issue was triaged from [`bugs/dan/0-needsPackage-unadorned`](https://github.com/Macaulay2/M2/blob/388c1ff0ce30d83751dea7bc7eac77fdc1305dd7/bugs/dan/0-needsPackage-unadorned), one of the 857 files removed from the pre-GitHub `bugs/` tree by [`d2c8d27826`](https://github.com/Macaulay2/M2/commit/d2c8d27826) and catalogued in [#36](https://github.com/Macaulay2/M2/issues/36). **The commentary below was written by Claude (Claude Opus 5, via Claude Code)**, not by @d-torrance, whose account posted it -- please weigh it accordingly.

### The original file, verbatim

```text
-- -*- M2 -*-

-- needsPackage and loadPackage need an optional argument, such as Using=>true. When true, behavior is as now.
-- When false, a different global dictionary is put on the dictionaryPath that has just the synonym symbols (containing
-- "$") in it.
```

### Where it stands today

`needsPackage` still has no `Using` option. Its options are `LoadDocumentation`, `Configuration`,
`FileName`, `Reload` and `DebuggingMode`.

### What the file asks for

`needsPackage(..., Using => false)`: load the package but put a dictionary on `dictionaryPath` holding
only the **synonym** symbols — the ones containing `$` — so the package's names are reachable
explicitly (`foo$Pkg`) without being dumped into scope unadorned.

### Why it is worth having

This is the missing middle between the two options that exist. `PackageImports` loads without
importing symbols at all; `PackageExports` imports them *and* re-exports them to your own users. There
is nothing that says "I want these names, but only via their qualified spellings, and I am not passing
them on" — which is exactly what a package author wants when a dependency's names collide with their
own.

**#4537** is the sweep that trips over this gap: 34 packages still use `needsPackage` because neither
existing option does what they need.

### Notes for whoever picks this up

The synonym symbols already exist — the shadowing warning M2 prints ("use the synonym `graph$0`")
depends on them — so this is about which dictionary goes on the path rather than about creating new
names.

_{`open` · disposition `issue` · source of truth: [`bug-triage/catalog.tsv`](https://github.com/d-torrance/M2/blob/bug-triage/bug-triage/catalog.tsv)}

Start at the needsPackage entry point and review its existing options, especially PackageImports and PackageExports, to understand how dictionaries are placed on dictionaryPath. Implement the Using => false behavior so only synonym symbols remain reachable through qualified names, then verify that unadorned package symbols are not imported.

Written by the indexing model from the issue text.