refactor: re-skin UI with native iOS components

Replace the Opal-style custom presentation with the bare iOS design
language, keeping the backend, flows, and accessibility identifiers:

- Home: NavigationStack + List; rules now presented as list rows with
  kind icon, block summary, and trailing live status; '+' in the toolbar
- New Rule: plain list of rule types and presets; editor still pushed
  via navigationDestination
- Editor: native Form (DatePicker rows, day circles with summary in the
  section header, toggle rows with footers, stepper rows); create
  commits with a prominent 'Add Rule' button replacing Hold to Commit;
  edit uses toolbar Done plus red Disable/Delete rows
- Detail: sheet with inline title + status caption, LabeledContent
  rows; Edit Rule pushes the editor natively
- Default color scheme: drop forced dark mode and custom tint; system
  appearance and accent throughout
- Delete Theme, HoldToCommitButton, RuleCardView and custom chrome
- Use concrete Color.primary/secondary in button row labels (the
  hierarchical styles resolve against the button tint)
- Tests: 93 passing; only delta is holdToCommitButton press →
  commitRuleButton tap in 5 call sites
- Spec: add §6 mapping the original presentation to the native one

docs/RULES_FEATURE_SPEC.md

@@ -329,3 +329,23 @@ enum SelectionMode: String, Codable { case block, allowOnly }
 - Onboarding flow, paywall ("You know Opal works. Make it permanent."),
   Home tab gem/score UI, Timer tab (one-off focus sessions, "Leave Early?"
   friction screen), notification nudges ("Complete Your Setup").
+
+---
+
+## 6. Native UI re-skin (current presentation)
+
+Severed has since replaced the Opal-style custom presentation with the bare
+iOS design language, keeping the backend (models, logic, services), the
+flows, and the accessibility identifiers intact. Sections 1–5 remain as the
+reference for *what* the feature does; presentation now maps as follows:
+
+| Spec element | Native presentation |
+|---|---|
+| Apps home | `NavigationStack` + `List`; "Blocked Apps" and "Rules" sections; **rules are list rows** (kind icon, name, block summary, trailing live status — green when active); "+" toolbar button |
+| Rule detail | Sheet with inline nav title (name + "Schedule, 6h left" caption), `LabeledContent` rows, "Edit Rule" row pushes the editor; hard-locked rules show a lock row instead |
+| New Rule | `List` with a "Rule Type" section and preset sections as plain rows; editor pushed via `navigationDestination(item:)` |
+| Rule editor | Native `Form`: `DatePicker` rows, day-circle row with the summary in the section header, toggle rows with footers, stepper rows. Create commits with a prominent **"Add Rule"** button (replaces Hold to Commit); edit uses toolbar **Done** plus red Disable/Delete rows |
+| Onboarding / app picker | System styling, `.borderedProminent` buttons, default color scheme (no forced dark, default accent) |
+
+Dropped custom components: `Theme`, `HoldToCommitButton`, `RuleCardView`,
+icon-pair/circle-button chrome.