[Anthony Sligar (sligara7)]

Adds pdftools.shutter.TwoButtonShutter and FilterBank, and builds fb (XF:28ID1B-OP{Fltr:1..4}) in the profile.

• Each filter fires Cmd:Opn-Cmd / Cmd:Cls-Cmd and waits for Pos-Sts; 1/"Open" takes it out of the beam, 0/"Close" puts it in, and it reads back "Open"/"Close" (as the old profile's read() patch did). PV names and meaning checked against the old 11-motors.py and the cs-studio-xf OCM screen.
• One device fb replaces the old fb (open commands only) and fb_two_button_shutters/fb2; plans use fb.flt4 where they used fb2.flt4.
• No re-actuation retry (nslsii's TwoButtonShutter re-fires up to 10 times); as in hextools' Shutter, a move that does not finish times out.

Verified: mock tests (PV names, commands fired, readback, timeout, profile boots in mock mode with fb). Not run on the beamline.

[Copilot]

🔵 Needs a closer look

Live command and readback behavior for beamline attenuation hardware remains unverified and needs human confirmation.

No open issues 🎉

What changed in this PR

Adds a four-filter bank to the PDF beamline profile, using two-button actuators with command execution and position readback.

Changes:

• Adds TwoButtonShutter and FilterBank, supporting numeric and string targets, status-based completion, and timeouts.
• Exposes the filter bank as fb in the collection profile.
• Adds mock tests for PV names, commands, readback, timeout behavior, and profile initialization.

File	Description
tests/​test_utils.py	Checks that the mock profile exposes fb.
tests/​test_filter_bank.py	Tests filter commands, readback, validation, and timeouts.
src/​pdftools/​shutter.py	Implements two-button actuators, mock behavior, and the four-filter bank.
src/​pdftools/​profiles/​collection.py	Creates fb with the beamline filter PV prefix.

_{Review effort: Balanced}