docs: 新增 CHANGELOG.md，记录 1.0.0 版本完整变更历史

按主题分类整理从项目初始化到当前版本的所有变更：
- 项目基础架构与工程配置
- 日历核心视图系统（月/周/年）
- 折叠动画与手势交互
- 中式日历（农历、节气、节日）
- 个人排班系统
- 视觉设计与动画系统
- 底部卡片与信息展示
- 页面导航与预测性返回手势
- 性能优化与构建测试

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

CHANGELOG.md

@@ -0,0 +1,148 @@
+# Changelog
+
+All notable changes to the YaYa project are documented in this file.
+
+The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.1.0/),
+and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
+
+## [1.0.0] - 2026-05-20
+
+### Added
+
+#### Project Foundation
+- Kotlin Multiplatform project setup targeting Android and iOS with Compose Multiplatform
+- Two-module architecture: `:shared` (UI + business logic) and `:androidApp` (thin Android shell)
+- AGP 9.2.1, Gradle 9.5.1, Kotlin 2.3.21, JVM target 17
+- Compile SDK / target SDK 37, minimum SDK 24
+- Version catalog at `gradle/libs.versions.toml`
+- Dynamic version name generation: `baseVersion + git hash + buildDate`
+
+#### Calendar Core Views
+- **Month View**: 6x7 day grid with dynamic row count (4/5/6 weeks) based on actual month shape
+- **Week View**: Single-week horizontal pager activated by collapsing the month view
+- **Year View**: 4x3 mini-month grid with swipe-based year navigation and Hero Zoom transition
+- **Infinite Paging**: `Int.MAX_VALUE` virtual pages centered at `Int.MAX_VALUE / 2`, enabling boundless month/week/year navigation
+- ISO 8601 week numbering with Monday as the first day of the week
+- Today indicator with border outline; selected-today state uses `primaryContainer` for softer visual treatment
+- Non-current-month days are grayed out for visual clarity
+- Auto-select today (if within range) or first day / Monday on page changes
+- Click month header to jump back to today
+- Cross-month week selection: intelligently selects the appropriate date based on swipe direction
+
+#### Collapse / Expand Animation
+- Drag-driven month-to-week collapse gesture on the calendar grid
+- Spring-based snap animation that auto-settles to the nearest state on release
+- Two-phase whole-block slide-up collapse animation with fade-out for non-selected rows
+- Dynamic drag range computed from actual visual height change for 1:1 finger tracking
+- Fling velocity threshold (800 dp/s) for quick swipe snap
+- Collapse threshold set to 8% for easy fold/unfold triggering
+- Pull-down gesture to expand from collapsed week view back to month view
+- Week pager cross-fade transition to eliminate blank gaps during page switches
+
+#### Chinese Calendar (Lunar)
+- Lunar date display below each day number (using `tyme4kt`), showing month name on the first day of each lunar month
+- Twenty-four solar terms (节气) annotations
+- Traditional lunar festivals (春节, 端午, 中秋, etc.)
+- Western solar festivals
+- Legal holiday and compensatory workday badges (休/班) in the top-right corner
+- Priority-based annotation display: legal holidays > lunar festivals > solar terms > solar festivals > lunar day
+
+#### Personal Shift Scheduling
+- `ShiftPattern` data model with anchor date + cyclic sequence for periodic work/rest schedules
+- Independent from public holidays
+- Work/Rest capsule badge display on DayCell
+- Configurable legal holiday overlay toggle (default off)
+- Shift status tips in the bottom card
+
+#### Visual Design & Animations
+- Material 3 dynamic color scheme
+- System dark theme support with automatic light/dark `ColorScheme` switching
+- DayCell circular reveal animation with `updateTransition` for smooth state transitions
+- Month header slide + fade transition when month/week number changes
+- Page fade-in/fade-out transitions on CalendarPager and WeekPager
+- GIF elastic entrance animation on switch
+- 152 GIF assets displayed randomly based on selected date seed
+- Custom app icon resources for all densities and platforms (PNG + WebP)
+
+#### Bottom Card
+- Draggable bottom info card with drag handle
+- Selected date relative day description (今天, 昨天, 明天, N天前/后)
+- Gregorian and lunar date details
+- Shift status tips (WORK / OFF)
+- Random GIF display (140dp height)
+
+#### Navigation & Pages
+- About screen with app icon, name, dynamic version, and open-source license entry
+- Licenses screen listing all third-party dependency licenses
+- Floating Action Button (FAB) with zoom-animated menu and scrim close
+- Page navigation with direction-aware slide + fade transitions
+- Android 13+ Predictive Back gesture with follow-finger displacement/scale animation
+- BackHandler expect/actual for cross-platform back gesture interception
+
+#### Performance Optimizations
+- `ComposeTrace` cross-platform trace markers for Perfetto / Systrace analysis
+- `graphicsLayer(translationY)` replacing `offset(Dp)` to avoid per-frame layout passes
+- SolarDay static cache to eliminate repeated object creation during pager switches
+- MiniMonth pure Canvas rendering: eliminated 96 Text component measurement overhead
+- Year view / month view coexistence in composition tree with `Modifier.alpha` control (avoiding whole-tree destruction)
+- Precomputed dp-to-px conversions and TextLayoutResult caches
+- Pager cache optimized (`beyondViewportPageCount = 0`)
+
+#### Build & Testing
+- R8 code shrinking and resource optimization with ProGuard rules
+- ABI filtering (`arm64-v8a`, `armeabi-v7a`)
+- App Bundle language/density/ABI splits
+- Unit tests for `CalendarViewModel`, `CalendarUtils`, and `ShiftPattern`
+- `kotlinx-coroutines-test` for coroutine-based ViewModel testing
+- ComposeTrace host test fallback (silently ignores when Trace API is not stubbed)
+
+#### Documentation
+- `CLAUDE.md` with project architecture, conventions, and build commands
+- `DEVELOPMENT.md` with setup, build, test, and Perfetto trace analysis guide
+- `COMMENTS.md` with commenting and KDoc conventions
+- `README.md` with feature overview and tech stack
+
+### Changed
+
+- Row padding increased from 4dp to 6dp for better touch targets
+- Selected-state animation duration reduced from 250ms to 150ms for snappier feedback
+- Weekday header moved out of pager to remain fixed across page swipes
+- Card gap spacing animates with collapse progress (24dp expanded → 12dp collapsed)
+- Year view title bar displays lunar干支+生肖 year (e.g., 「丙午马年」) with a "今年" button for quick return
+- FAB fixed to bottom-left of screen instead of tracking BottomCard height
+- Menu scrim changed to fully transparent without fade animation
+
+### Fixed
+
+- First-frame flicker by deferring row height until measured
+- Calendar height jitter when collapsing to week view
+- Swipe interpolation discontinuity during month transitions
+- Collapse drag not tracking finger (now uses dynamic dragRange)
+- BottomCard positioning during collapse animation
+- Flash when expanding after navigating months in collapsed state
+- Week number baseline alignment stability during AnimatedContent transitions
+- Year view stale year display on enter
+- Year view missing scale animation on first launch
+- "Today" button title bar jitter: replaced conditional rendering with alpha fade
+- Folded state cross-month date not grayed out in week view
+- Theme switching transparency issues by adding explicit background colors
+- Predictive back gesture failure and end-of-animation flash on certain devices
+- Back animation residual transition eliminated with `snapTo`
+- Icon colors now adapt to `MaterialTheme` instead of hardcoded white
+
+### Removed
+
+- MonthHeader click-to-toggle-year-view (replaced by FAB menu)
+- Year view arrow navigation (replaced by swipe gesture)
+- Shift badge background circle for lighter visual weight
+- Default ripple effect on DayCell (replaced by circular reveal animation)
+- Aliyun Maven mirrors (switched back to Maven Central / Google)
+- Unused Compose runtime ProGuard keep rules
+
+## [Unreleased]
+
+- No unreleased changes at this time.
+
+---
+
+[1.0.0]: https://github.com/xfy/yayacal/releases/tag/v1.0.0