feat: typed settings fields, timeline zoom, faster dev builds

Footage budget, clip hotkey length and bookmark before/after are now typed
fields (m:ss or seconds), validated on Enter or blur and reverted when out of
range. Scrolling over the session timeline zooms around the pointer (down to
10 s) and scrolling sideways or with Shift pans, with a Fit button.

Settings felt slow because GPUI ran unoptimised: dev builds now optimise
dependencies, taking first frames from 200-300 ms to about 15 ms. Adds
rig-pointer, a virtual pointer for driving the interface in the headless
rig, which verified the fields, zoom and timeline dragging.

README.md

@@ -85,7 +85,9 @@ cargo test --locked --workspace
 cargo clippy --locked --target x86_64-pc-windows-msvc -p clipbin-core -p clipbin-obs -p clipbin-probe --all-targets -- -D warnings
 ```
 
-Recording validation on Linux, headless: `scripts/validate/linux-rig.sh`. Interface screenshots, headless: `scripts/rig/screenshot-ui.sh` (screens: sessions, session, clips, settings, failed, empty).
+Recording validation on Linux, headless: `scripts/validate/linux-rig.sh`. Interface screenshots, headless: `scripts/rig/screenshot-ui.sh` (screens: sessions, session, clips, settings, failed, empty). The rig has no input devices; `rig-pointer` drives a virtual pointer (`move`, `click`, `down`/`up`, `scroll`, `sleep` on stdin) and `wtype` types. `CLIPBIN_TRACE_FRAMES=1` logs frame times.
+
+Development builds optimise dependencies (`[profile.dev.package."*"]`): unoptimised GPUI made screens noticeably slow, with first frames of 200–300 ms.
 
 The core can also be checked without native UI dependencies: