feat(camera): add Logitech webcam support

[davidbudnick]

Context

OpenLogi only managed HID++ devices — Logitech UVC webcams were invisible. This adds first-class webcam support: enumeration, live preview, and device-level image controls written over USB to the camera's own registers, so adjustments carry into Google Meet, Zoom, and OBS rather than living only in our preview.

Note

Platform support: macOS has the full feature (AVFoundation preview + IOKit controls) and is verified end-to-end on a StreamCam. Windows matches it — DirectShow enumeration and controls (IAMVideoProcAmp / IAMCameraControl) plus a Media Foundation live preview/snapshot backend (IMFSourceReader, RGB32) — and compiles clean against x86_64-pc-windows-msvc, but has not yet been exercised on real Windows hardware. Linux builds against stubs and shows no cameras.

Demo

• Plug in a Logitech webcam (tested end-to-end on a StreamCam) → it appears on the Devices page with its product render.
• The Camera tab shows a 720p/30 fps live preview beside the controls: Lens (Zoom / Focus / Exposure) and Image (Brightness / Contrast / Saturation / Sharpness / White balance) sliders, Auto toggles, one-click profiles (Default / Streaming / Video call / custom), and double-click-to-reset on any row. Dragging an auto-gated slider (focus / exposure / white balance) takes the control over to manual in one device write, G HUB-style.
• The camera streams only while its tab is visible (LED off otherwise); settings persist to config.toml and re-apply after unplug/reboot.
• CLI: openlogi camera get, openlogi camera set brightness 140, openlogi snapshot

Changes

• openlogi-camera crate — AVFoundation capture plus IOKit UVC controls on macOS (Processing Unit and Camera Terminal, 4-byte exposure payloads, AE-mode bitmap, batched into a single device-seize); Media Foundation capture plus DirectShow enumeration/controls on Windows: capture.rs, capture_windows.rs, uvc.rs, uvc_windows.rs, controls.rs, capture_types.rs
• Camera tab — zero-copy 720p preview beside a sectioned control panel with Auto chips and profiles: camera_preview.rs, camera_controls.rs, app.rs
• Asset pipeline — cameras join the depot sync; the device_camera_image manifest key and base-model variants fetch and resolve; marker-less camera metadata parses: asset/sync.rs, asset/images.rs, openlogi-assets
• Config — CameraControls becomes a name-keyed map (existing TOML loads unchanged) with per-camera profiles and active selection: config.rs, state.rs
• CLI — openlogi camera get/set for every control and auto toggle; openlogi snapshot writes a PNG: cmd/camera.rs, cmd/snapshot.rs
• Carousel — fixed-width no-shrink cards, selection-tracked scrolling, floating arrows that stop click propagation: carousel.rs

Notes

• The Camera permission row appears in Settings only when a webcam is present; strings are translated for all 21 locales.
• Deferred follow-ups: pan/tilt (compound 8-byte control, needs motorized hardware), vibrance (Logitech vendor XU), filters, per-app persistence.

[greptile-apps]

Greptile Summary

This PR adds Logitech webcam support across the app. The main changes are:

• New openlogi-camera crate for camera discovery, capture, and UVC controls.
• Camera controls UI with live preview, sliders, auto toggles, and profiles.
• CLI commands for camera control and snapshots.
• Asset, config, device-list, and permission updates for webcam devices.
• Platform backends for macOS and Windows, with Linux stubs.

Confidence Score: 5/5

This looks safe to merge.

• No blocking issues found in the changed code.
• The reviewed follow-up candidates overlap with existing review feedback or do not require a separate fix.

Important Files Changed

Filename	Overview
crates/openlogi-camera/src/uvc.rs	Adds macOS UVC device matching, camera topology parsing, and batched control writes.
crates/openlogi-gui/src/components/camera_controls.rs	Adds the camera controls panel with saved-state reapply, profile handling, and device-write failure paths.

_{Reviews (5): Last reviewed commit: "Merge branch 'master' into feat/logitech..." | Re-trigger Greptile}

[greptile-apps]

Ambiguous Fallback Remains

When location_hint(unique_id) is None, this branch still keeps the first Logitech UVC device as a fallback. The GUI passes the selected camera's AVFoundation ID into this backend, so an ID this parser cannot turn into a location hint can still make controls for one Logitech webcam write to whichever Logitech webcam IOKit enumerates first. With two attached Logitech cameras, this should fail closed instead of picking a best-effort device.

[greptile-apps]

Failed Profile Stays Active

When apply_settings() fails here, the panel rebuilds from live hardware but keeps the previous camera_active_profile in state. If a custom profile was active, applying another profile fails, and the user then edits a slider, sync_active_custom() still sees the old custom profile as active and overwrites that saved profile with the rebuilt live values. Clear or invalidate the active profile on this failure path before rebuilding.

[AprilNEA]

Fantastic feature — thanks for the thorough write-up and the end-to-end macOS testing on the StreamCam. A few things need to happen before it can land, and they're much easier from your side since you have the hardware:

1. Rebase onto master. It's ~60 commits behind and now conflicts (settings-page overhaul, Windows follow-ups, wheel/hotplug work, and the 20 locale files). Fresh conflict resolution from someone who knows the camera code will be far more reliable.

2. Move the macOS FFI to objc2. The whole workspace migrated off raw objc 0.2 to objc2 since you opened this — openlogi-hook, openlogi-inject, openlogi-agent, and openlogi-gui are all on it now — so openlogi-camera should match (the "same objc 0.2 as the GUI" note is now stale). That means Retained<T> for ownership, MainThreadMarker where the AVFoundation calls need the main thread, etc. The pattern in crates/openlogi-gui/src/platform/ and crates/openlogi-agent/src/tray.rs is the reference — it keeps the unsafe_code = "deny" + typed-ownership convention consistent across the workspace.

3. Windows is still untested on hardware — worth a pass on a real Logitech cam before shipping it first-class (or we land macOS-first and flag Windows experimental).

Happy to review again once it's rebased and on objc2. Really nice work.