fix(panel): convert sensors popover to native Singularity widgets, make it responsive

[perlowja]

Summary

Split out of #26 (OCS wallpaper browser), which had accidentally bundled sensors-popover work alongside the unrelated wallpaper/Bing browser changes -- per review feedback on that PR, this is the sensors-only portion, isolated to src/components/panel/panel.vala (no other file is touched, and no wallpaper code is present here).

• Converts the SensorsIndicator popover from a hand-built Gtk.Box/Label/Button tree to Singularity.Widgets.PreferencesGroup/PreferencesRow/ActionRow -- the same controls the rest of the desktop surface (desktop_page.vala, calendar_view.vala) already uses for grouped lists.
• Makes the popover layout responsive.
• The one straggler raw Adw.PreferencesRow (in append_compact_row()) is swapped for Singularity.Widgets.PreferencesRow, so this surface is 100% libsingularity widgets with no direct libadwaita usage.

Behaviour preserved: every severity threshold, MAX_ROWS_PER_GROUP cap, polling interval, schema-key guard, map/unmap gate, and the synchronous-refresh-on-popover-open path are unchanged. The heat bar stays a raw Gtk.DrawingArea (Gtk.LevelBar's battery-style level-low/level-high semantics paint every short bar red -- documented inline where make_heat_bar() is defined).

Follow-up: panel summary severity colours restored (b51a24e)

The first revision of this PR also restyled the compact panel chip onto the clock's typography, which silently dropped the per-metric severity colouring main already ships. That was an unintended regression and has been reverted: theme_color_hex(), markup_segment(), severity_color_name(), the primary_kind/primary_severity selection and the use_markup chip assembly are now byte-identical to main, as are the sensors-indicator / sensors-summary / flat CSS classes they depend on. git diff main -- src/components/panel/panel.vala shows no delta in any severity, colour or markup code path; only the popover widget conversion and responsive layout remain.

Test plan

• meson setup + meson compile clean on a fresh checkout (arm64 build host) -- links singularity-desktop with no errors and no new panel.vala warnings beyond the pre-existing ones (local functions are experimental, the GTK 4.10/4.12 deprecations, all of which main also emits).
• meson test -- 8/8 pass.
• Manual: open the sensors popover on hardware and confirm the compact-row layout and responsiveness look correct (no behavioural change intended, but worth a human look given the widget swap).

[chatgpt-codex-connector]

Codex Review Summary

This comment shows the latest Codex review activity on this pull request.

Review	Status	Commit	Review trigger
📝 Code Review	✅ Completed 2026-09-12T19:27:39.600553Z	abdfe43	PR opened

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[mirkobrombin]

This also removes the severity colors from the panel summary, and the PR body exposes Claude attribution, so restore the existing status semantics and remove that metadata before re-review.

[perlowja]

Thanks — both fair, and the severity-colour one was a real regression on my side, not a deliberate change.

Severity colours restored (e2e323f). The cause was that I also restyled the compact panel chip onto the clock's typography (clock / clock-button, inherited colour) while doing the widget conversion. That was gratuitous, and because the chip's colouring is done with Pango markup rather than CSS classes, switching to inherited colour meant the whole markup path went with it. Restored verbatim from main:

• theme_color_hex() — resolves a named theme colour (error_color / warning_color / text_color / success_color / accent_color) at render time, so it still follows a light/dark switch.
• markup_segment() and the summary_label.use_markup = true chip assembly.
• severity_color_name() — the Severity → named-colour mapping.
• The primary_kind / primary_severity selection, including the hottest-reading fallback carrying its own kind, which is what keeps the colour describing the number actually shown.
• The sensors-indicator / sensors-summary / flat classes those depend on.

git diff main -- src/components/panel/panel.vala now shows zero delta in any severity, colour or markup code path — the only remaining diff is the popover widget conversion and the responsive layout this PR is actually for. I also traced that the restored code is live rather than re-added dead code: it reads the same reading.severity and capacity_severity(util.memory_fraction) values that the popover rows (untouched here) already consume.

PR body cleaned. The trailing attribution block is gone.

Going forward I'll use the disclosed form you prefer on commits, which e2e323f already carries:

Assisted-by: Claude Code:claude-opus-5
AI scope: <what was generated>

Verification on the new head: meson setup + meson compile link clean (arm64), no new panel.vala warnings beyond the pre-existing ones main also emits, and meson test is 8/8.

[mirkobrombin]

The widget conversion still has no completed visual check, so please attach narrow and wide screenshots of the real sensor popover before merge.

[perlowja]

@mirkobrombin Visual check completed. These are headless captures of the real SensorsIndicator popover from the currently deployed shell source (fd4eb8b8f51e4f3a6c72c0aa48e642430103780a, which contains this PR plus the subsequent integrated fixes), rendered with deterministic Sky1-like sensor data.

• Narrow: 1024px logical monitor, below the widget's 1280px breakpoint, so the popover uses one column.
• Wide: 1600px logical monitor, above the breakpoint, so it uses two balanced columns.

The captures show the native GTK rows, inherited stock theme states (dim-label, warning/error), heat bars, grouped/ungrouped control, clocks, utilization, memory, and storage without synthetic pointer input.

Narrow (single column)

Wide (two columns)

The image-hosting branch contains only these two PNG artifacts; no code from the integrated source tree was committed to this PR branch.