feat: v1.5 — plan editor, voice prompts, UI polish

Major features:
- Training plan editor: edit preset days/duration per plan (in-place
  override via custom_plans storage; preset ids preserved so existing
  records stay valid)
- Voice prompts at 4 fixed points during training (halfway / 30s /
  10s / done) via Tencent Cloud TTS (cloudfunctions/tts + utils/voice.js)
- Free-training button: switched from outline (transparent) to ghost
  variant (theme-tinted) for visual weight

Bug fixes:
- 4 functional pages: SVG data URIs failed to render in WeChat because
  '\#' in colors was parsed as a data-URI fragment delimiter. encode the
  whole SVG via encodeURIComponent in utils/icons.js build().
- Old records (saved before id field was added) could not be deleted
  (data-id was empty, triggered defensive guard). Backfill stable
  legacy-<month>-<index>-<duration> ids in getRecords() and persist.
- settings.js plan-row editor button event was bubbling up to the row's
  bindtap (which also fired onSelectPlan). Wrapped in catch:tap.

UI:
- Settings page: 3 hardcoded plans replaced with dynamic buildPlansList
  that overlays custom_plans on top of presets
- Plan editor: bottom-sheet modal in settings page (regular view, not
  ui-modal — WeChat custom component root element drops position:fixed
  in this runtime)
- Free-training button: rounded pill style, full-width, 24rpx gap from
  primary action; bottom sheet uses max-height: 88vh + internal scroll
- Version bumped to v1.5, last updated 2026-06-10

Removed:
- Daily reminder section (dailyReminder / reminderTime) — replaced by
  the 4 voice prompts which cover the same user need without requiring
  long-term scheduling that WeChat mini-programs can't actually do

Misc:
- utils/plan.js refactored to formula-driven: presets declare
  totalDays/startTarget/increment/cycleDays, days[] is generated. Same
  formula applies to custom plans.
- Timer _remind() guards each prompt on minimum duration so short
  free-mode sessions don't fire 'last30' at the start
- Cloud storage cloud_plans field added to data push payload; restored
  on first install via _restoreFromCloud
- .gitignore added for local AI tool caches (.reasonix/, reasonix.toml,
  .codegraph/daemon.pid)

utils/theme.js

@@ -94,20 +94,22 @@ const setTheme = (id) => {
   return theme
 }
 
-const applyThemeToPage = (self) => {
-  const theme = getCurrentTheme()
-  self.setData({
-    theme,
-    themeStyle: `${BASE_VARS}--primary:${theme.primary};--primary-light:${theme.primaryLight};--primary-bg:${theme.primaryBg};--primary-rgb:${theme.primaryRgb};`
-  })
-  _setNavBarColor(theme.primary)
-}
-
 const getThemeStyle = (theme) => {
   const t = theme || getCurrentTheme()
   return `${BASE_VARS}--primary:${t.primary};--primary-light:${t.primaryLight};--primary-bg:${t.primaryBg};--primary-rgb:${t.primaryRgb};`
 }
 
+const applyThemeToPage = (self) => {
+  const theme = getCurrentTheme()
+  const nextStyle = getThemeStyle(theme)
+  // Skip setData if nothing changed — avoid unnecessary re-renders on every onShow
+  if (self.data && self.data.themeStyle === nextStyle) {
+    return
+  }
+  self.setData({ theme, themeStyle: nextStyle })
+  _setNavBarColor(theme.primary)
+}
+
 module.exports = {
   THEMES,
   DEFAULT_THEME_ID,