Accessibility follow-ups: insights contrast, stat grouping, lint sweep

[kasnder]

Refs #636

Summary

Addresses the three "Candidate follow-ups" items from the a11y tracking issue that were in scope for automated work (color contrast, stat grouping, lint triage). The remaining items (on-device TalkBack pass, live-region announcements, focus/traversal order review) are intentionally left for a follow-up, as noted in the issue.

1. Color-contrast fixes (insights hero card)

app/src/main/res/layout/item_insights_header.xml sits on the bg_insights_hero gradient (#8B0000 → #B71C1C → #D32F2F, darkest to lightest). Contrast was measured against both the darkest stop (best case) and the lightest stop (worst case, where the text sits over #D32F2F), using the standard WCAG relative-luminance formula.

Element	Before	Contrast (darkest / lightest stop)	After	Contrast (darkest / lightest stop)
"Last 7 Days" subtitle (13sp bold, alpha 0.9)	white @ 90% alpha	8.2:1 / 4.28:1 (fails 4.5:1)	white @ 95% alpha	9.2:1 / 4.62:1 (passes)
Stat labels: "Tracker Hosts Contacted" / "Tracking Companies" / "Blocked" (11sp, alpha 0.85)	white @ 85% alpha	7.0:1 / 3.96:1 (fails)	white @ 95% alpha	9.2:1 / 4.62:1 (passes)
Protection % value (36sp bold)	hardcoded #A5D6A7	6.09:1 / 3.03:1 (marginal, large-text-only)	#F1F8E9 (pale green, same accent family)	9.22:1 / 4.59:1 (passes AA for all text sizes)
Stat numbers (36sp bold), "Last 7 Days" icon, Share button	white, full alpha	4.98:1–10:1	unchanged	unchanged

All text now clears 4.5:1 against the gradient's lightest stop, not just the 3:1 "large text" bar. The green accent on the percentage was kept (spirit of the original design) but lightened enough to pass at its actual (non-large-text-only) contrast requirement.

2. Group stat number + label for TalkBack

item_insights_header.xml: each of the three stat blocks (tracking attempts, tracker companies, protection %) is now a single focusable="true" LinearLayout container; the number and label TextViews inside are marked importantForAccessibility="no". InsightsHeaderAdapter.onBindViewHolder sets a combined contentDescription on each container (e.g. "128, Tracker Hosts Contacted"), so TalkBack reads each metric as one swipe stop instead of two.

3. Lint accessibility triage

Ran ./gradlew :app:lintGithubDebug (full report generated despite the task exiting non-zero on pre-existing, unrelated errors — see Notes). 24 ContentDescription findings triaged:

Fixed (cheap, in this PR):

• AdapterAccess.java (access.xml ivBlock) — per-connection blocked/allowed icon now gets a contentDescription (mirrors the pattern already used for the access-log adapter in Accessibility sweep: label remaining unlabeled controls (#231) #634).
• ActivityMain.java (actionmain.xml ivQueue / ivMetered) — "busy" and "metered network" header icons now get a contentDescription built from their existing toast strings (msg_queue, msg_metered).
• WidgetMain.java (widgetmain.xml ivEnabled) — home-screen widget toggle now gets a state-aware contentDescription via new strings widget_toggle_enable_description / widget_toggle_disable_description.
• 13 purely decorative icons marked importantForAccessibility="no" (each already has an adjacent text label conveying the same information): 12 icons in legend.xml, plus the onboarding illustrations in item_onboarding.xml / item_onboarding_blocking_mode.xml, and the insights "no data" empty-state icon in activity_insights.xml.

Remaining (listed, not fixed here):

• actionmain.xml ivIcon (master rocket logo / long-press "about" trigger) — ambiguous purpose (branding + hidden gesture), needs a product decision on wording rather than a mechanical fix.
• log.xml ivConnection / ivInteractive — lint false positive; these already get a dynamic contentDescription set in AdapterLog.java from Accessibility sweep: label remaining unlabeled controls (#231) #634, just not statically declared in XML.
• traffic.xml ivTraffic — a live-drawn traffic-rate graph with no static text equivalent; needs a proper dynamic/summary description, out of scope for a "cheap fix".
• All other lint categories (RtlHardcoded, UseCompoundDrawables, HardcodedText, etc.) are non-accessibility or pre-existing and out of scope for this issue.

Not in this PR (per issue, left for follow-up)

• On-device TalkBack pass for Add dynamic accessibility labels to app-list Internet toggle (#231) #625 / Accessibility sweep: label remaining unlabeled controls (#231) #634.
• Live-region / dynamic state-change announcements.
• Focus/traversal order review on main and details screens.

Notes

• New strings (widget_toggle_enable_description, widget_toggle_disable_description) added to base English strings.xml only, matching the Add dynamic accessibility labels to app-list Internet toggle (#231) #625/Accessibility sweep: label remaining unlabeled controls (#231) #634 pattern; translations follow via the normal localization process.
• ./gradlew :app:lintGithubDebug currently fails to exit 0 due to pre-existing, unrelated resource-linking/format errors in translated strings (e.g. a mistranslated @string/... reference in values-uk-rUA, and a % formatting issue in values-da-rDK) — these predate this PR and are a known symptom of the Crowdin string-recreation issue tracked separately. The lint report itself still generates correctly and was used for the triage above.
• ./gradlew :app:compileGithubDebugJavaWithJavac passes.

🤖 Generated with Claude Code

[kasnder]

Review finding — localizable accessibility sentence (InsightsHeaderAdapter.java): The new content descriptions assemble value, punctuation, and label directly in Java, which hard-codes English word order. Languages that place the label first or use another separator cannot translate the complete announcement. I have prepared a fix using a formatted string resource with reorderable %1$s and %2$s placeholders.