feat(ui): month card grid + week timeline, wire view switcher

Replace the throwaway debug screen with the first real calendar UI and a
functional Month <-> Week switcher, on Material 3 Expressive.

Month view (S1):
- Material 3 Expressive card-per-day grid; only the current month's weeks
  render (neighbouring days left blank)
- per-day event dots with "+N" overflow, today via primaryContainer
- spring-based press feedback from the active motion scheme
- swipe + drawer navigation, Loading/Failure/Success states

Week view (S2):
- vertical time schedule with overlap-resolved lanes (per-day clipping,
  midnight spanning, instant events)
- all-day / multi-day events as connected horizontal spans
- single scroll container (gutter + day columns stay aligned), columns
  bundled in a rounded container, noon-centred on load
- top section colour-shifts with the app bar on scroll; swipe navigation,
  three states

Shared / infra:
- CalendarHost holds the active view; RootScreen renders it post-permission
- ui/common building blocks: CalendarDrawer, CalendarFailure,
  ViewSwitcherPill, pastelize, observable locale, M3 Expressive slide
  transition (motionScheme fastSpatialSpec)
- unit tests for the week layout (lanes, clipping, all-day spans)
- build: compileSdk 37, material3 pinned to 1.5.0-alpha21 for Expressive

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

.planning/ROADMAP.md

@@ -6,8 +6,8 @@
 |---|---|---|
 | v0.1 | Foundation & CI | complete |
 | v0.2 | Data Layer & Permission Flow | complete |
-| v0.3 | Month view | pending |
-| v0.4 | Week view | pending |
+| v0.3 | Month view | in progress |
+| v0.4 | Week view | in progress |
 | v0.5 | Day view | pending |
 | v0.6 | Event Detail Sheet | pending |
 | v0.7 | Filter & Settings | pending |

.planning/STATE.md

@@ -1,11 +1,12 @@
 # Calendula — Current State
 
-*Last updated: 2026-06-08*
+*Last updated: 2026-06-10*
 
 ## Status
 
-**Milestone:** v0.2 — Data Layer & Permission Flow
-**Phase:** Plan 02 complete; UI-design iteration pending before Plan 03
+**Milestone:** v0.4 — Week view (in progress)
+**Phase:** Month + Week views implemented; cross-cutting wiring (detail sheet,
+filter, settings, jump-to-date) still stubbed
 
 ## Progress
 
@@ -13,11 +14,15 @@
 - [x] V1 design decisions resolved (App name "Calendula", icon, seed color)
 - [x] Plan 01 written and executed — foundation lands (theme, icon, i18n, Hilt, DataStore, CI green)
 - [x] Plan 02 written and executed — data layer + permission flow + debug screen
-- [ ] UI-design iteration (mockups for Month/Week/Day/Detail/Filter/Settings, all three states)
-- [ ] Plan 03 (Month view)
+- [x] Month view (S1) — 6-week grid, event dots, today marker, swipe nav, three states (replaces debug screen)
+- [x] Week view (S2) — time schedule with overlap-resolved lanes, all-day strip, swipe nav, three states
+- [x] View-switcher (M1) wired — cycles Month ↔ Week (Day joins once S3 lands)
+- [ ] Day view (S3)
+- [ ] Event-detail sheet (S4) — week/month event taps are currently no-ops
+- [ ] Filter sheet (M3), Settings (M4), Jump-to-date (M2) — drawer entries stubbed
 
 ## Next
 
-1. Iterate on UI design (mockups per screen, all three states)
-2. Write Plan 03: Month view
-3. Execute Plan 03 — Debug screen gets replaced by month view
+1. Day view (S3) — slot it into the view-switcher cycle
+2. Event-detail sheet (S4) — wire month-day and week-event taps to it
+3. Revisit month/week UI polish + shared anchor-date continuity across views