feat(nav): jump-to-date action in the navigation drawer

Add a "Jump to date" row to the drawer (under the View switcher) that
opens an M3 date picker and navigates the active view to the chosen day,
sliding in from the correct side. Wired across Month/Week/Day, each
seeding the picker with its visible anchor (day / week-start / 1st-of-month).

Extract the form's private date-picker into a shared
ui/common/CalendarDatePickerDialog so the event form and the drawer share
one picker; add goToDate() to the Month and Week view models.

Reprioritises the roadmap: jump-to-date is now next; duplicate-event drops
to the bottom as low-importance.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

.planning/ROADMAP.md

@@ -169,7 +169,9 @@ unblock a later item. Order is a plan, not a contract — revisit after each lan
 4. ~~Per-event color~~ *(shipped v2.4.0)* — palette calendars write
    `EVENT_COLOR_KEY` (sync-safe); local/opted-in calendars write a raw
    `EVENT_COLOR`; off-by-default setting for no-palette synced calendars
-5. **Duplicate event** *(next)* — detail action → prefilled create form; near-free on the tap-to-create prefill infra
+Tier 1's create/edit + calendars arc is effectively closed. **Duplicate event**
+was deprioritised (2026-06-17) as low-importance and dropped to the bottom of
+the sequence; the next item is now **Jump-to-date** (formerly Tier 2).
 
 (Tier 2+ numbering below shifts accordingly; ranking unchanged.)
 
@@ -223,7 +225,7 @@ Out of scope (no new settings *features* here) — this is a structure + style
 pass on the existing controls; new toggles ride in with their own features.
 
 **Tier 2 — navigation & daily-driver completeness**
-5. Jump-to-date — drawer date picker (un-cut from V1); cheap, fills the nav gap
+5. Jump-to-date — drawer date picker (un-cut from V1); cheap, fills the nav gap *(next)*
 6. Agenda view — the missing 4th view; serves daily-driver users *and* becomes the data source for the widget
 
 **Tier 3 — platform reach (depends on Tier 2)**
@@ -240,6 +242,10 @@ pass on the existing controls; new toggles ride in with their own features.
 - Locations & People — contact address picker (no-permission, one-shot) is the safe entry; OSM autocomplete needs INTERNET
 - Move event to another calendar — sync-adapter minefield (copy+delete model)
 
+**Bottom — deprioritised, not important**
+- Duplicate event (detail action → prefilled create form) — moved here
+  2026-06-17; cheap but low value, pick up only if asked
+
 **Unranked / fill-in** — pinch-to-zoom time scale, tablet/foldable layouts,
 full-text search, ICS file import. Pulled in opportunistically, not sequenced.