fix: editor usability and visual polish from UI scan

- Rule name is now an inline text field at the top of the editor; the
  pencil/rename button and alert are gone (it was unclear what the edit
  button did). Names are sanitized on commit: trimmed, falling back to
  the kind's default when emptied
- Day-of-week toggles fill the full row width with equal cells and
  >= 44pt tap targets
- 'Add Rule' commit button sits on a bar-material bottom inset so form
  content no longer collides with it while scrolling (found via
  computer-use scan; verified clean in a follow-up scan)
- Tests: 95 passing — new specs for the inline rename flow, day-toggle
  geometry, and name sanitization; three tests now scroll to reach
  bottom-of-form controls, matching real user behavior
- Spec §6 updated for the editor changes

SeveredTests/RuleModelTests.swift

@@ -110,6 +110,20 @@ struct RuleDraftTests {
         #expect(rule.hardMode)
     }
 
+    @Test("Sanitizing trims whitespace and falls back to the kind default")
+    func sanitizedName() {
+        var draft = RuleDraft(kind: .schedule)
+        draft.name = "  Deep Work  "
+        #expect(draft.sanitized().name == "Deep Work")
+
+        draft.name = "   "
+        #expect(draft.sanitized().name == "In the Zone")
+
+        var limitDraft = RuleDraft(kind: .timeLimit)
+        limitDraft.name = ""
+        #expect(limitDraft.sanitized().name == "Time Keeper")
+    }
+
     @Test("Preset drafts copy the preset's schedule")
     func presetDraft() throws {
         let preset = try #require(