breadman: rebuild settings as plain GTK4, fix AdwDialog sizing, present-ordering bug

The libadwaita-based settings screen (previous commit) had two real bugs a
closer look (and a screenshot from the real running app) caught:

- AdwSpinRow's internal GtkSpinButton has no width constraint of its own,
  so once the row was widened to 900px, the spin button stretched to fill
  it - the digits and +/- buttons ended up stranded behind a huge empty
  bordered box, the exact bug the design review flagged, just worse.
- bread-theme's shared `entry, spinbutton` rule outlines every field with
  an always-visible @overlay border, which on a light-cream overlay colour
  reads as a stark white outline against the dark theme.

Rather than keep fighting libadwaita's internal row/spin-button opinions
(there's no supported way to reach in and constrain them), settings.rs is
now plain GTK4 mirroring bos-settings' own Row.svelte/NumberField.svelte/
TextField.svelte design exactly: same tokens (12/16px row padding, ch-width
inputs, transparent-at-rest border, accent border only on focus), built on
a plain `list.boxed-list` for the native rounded-corner-run + divider
styling. Full control over sizing, no internal widget to hunt for.

Also fixed a real ordering bug in the editor AdwDialog conversion:
`open_editor` used to call `dialog.present()` internally before returning,
so callers that connected `dialog.connect_map` afterward (screenshot mode)
missed the signal entirely - it can fire synchronously inside `present`.
Presentation now happens at each call site, after wiring `connect_map`.
Also gave the dialog's content an explicit height/vexpand + min-content-
height, since the ScrolledWindow had none and the whole dialog was
collapsing to just its header bar.

breadpad-shared's bread-theme dependency also gets fixed here: it was
still pinned to an old GitHub-mirror tag (v0.2.8) while breadman pinned
the same crate to git.breadway.dev's dev branch - two different copies of
bread-theme compiled into the same binary, so breadman's actual runtime
CSS (built through breadpad_shared::theme) never saw any of the shared
stylesheet fixes above regardless of what breadman's own direct
dependency resolved to.

breadpad-shared/Cargo.toml

@@ -7,7 +7,7 @@ authors.workspace = true
 
 
 [dependencies]
-bread-theme = { git = "https://github.com/Breadway/bread-ecosystem", tag = "v0.2.8", features = ["gtk"] }
+bread-theme = { git = "https://git.breadway.dev/Breadway/bread-ecosystem", branch = "dev", features = ["gtk"] }
 anyhow.workspace = true
 tracing.workspace = true
 serde.workspace = true