[sbryngelson]

Closes #12.

Adds an opt-in `align-use-only` toggle (`true` / `false` / `"preserve"`, default `false`) that aligns `only:` across consecutive `use` statements at the same indentation:

```fortran
use m_derived_types, only: t_foo
use m_global, only: a, b
use m_mpi
use m_x, only: d
```

Behavior:

• Padding goes after the comma before `only:`.
• A `use` without `only:` stays in the group unchanged; a blank line, comment, preprocessor line, or other statement ends the group.
• Continuation lines of a `use` statement don't break the group, so it composes with `use-formatting = "one-per-line"`.
• Lines that would exceed `line-length` are left alone.
• `only:` inside a trailing comment and module names containing `only` (e.g. `m_only_stuff`) are handled; `use, intrinsic :: ...` works.
• Respects `! ffmt off` / `! ffmt on`.

Testing: 10 new integration tests in `tests/config_integration.rs`, plus a fuzz run of 2000 randomly generated modules (mixed casing, renames, continuations, `#ifdef`/Fypp/suppression interleaved, tabs, nested scopes, random config combinations) checking no crash, idempotence, token-identical output vs. the unaligned run, and exact match against an independent reference implementation of the rule. Docs and README updated.

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Review	Status	Commit	Review trigger
📝 Code Review	✅ Completed 2026-09-16T03:14:47.853516Z	cba0cc3	PR opened

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