fix(web): create events on the selected week column

[tyler-dane]

Summary

On another week, C always seeded the timed draft on the first visible day, and the timed form has no date field, so the draft was stuck there. Selecting a column with Shift+letter did not help: jump mode swallowed C, and a column with no events could not be selected at all.

• One target-day rule now serves every Week create gesture (C, Shift+C, Shift+Arrow place-create, typed digits): parked click, then the selected column, then the focused event's day, then today, then the first visible day. Creating spends the selection so chips never linger over the new draft.
• Any visible column can be selected with Shift+letter (or the bare letter after H), with or without events. That also makes the ⇧T header chip true for empty days.
• createTimedDraft / createAlldayDraft take the target day directly; Week no longer threads isCurrentWeek into the shortcut owner. Day view passes its date in view.
• Docs: docs/acceptance/shortcuts.md Scenario 5 and 12 plus the regression list.

Behavior change worth knowing: on the current week, C with a focused event now creates on that event's day, matching typed-time create since #3078.

Verification

• bun type-check, bun run lint, bun knip: clean.
• Targeted bun test files (matcher, jump hook, draft util, Week owner, Day grid, tips): all pass, including new cases for empty-column selection, C passthrough in jump mode, and Shift+R then C / Shift+C / Shift+Arrow landing on an empty Thursday.
• New e2e in e2e/timed/shift-hold-event-hints.spec.ts: next window, Shift+letter on the last column, C, save, assert the weekday. Passes locally with the other jump-hint and grid-parity specs.
• Preview (anon, next week): Shift+R then C opens the form with the draft in Thursday and clears the highlight; Shift+T then 1400 places a 2 PM draft on Tuesday; H then W moves the hour chips to Wednesday; Shift+R then Shift+C seeds an all-day draft on Thursday.
• bun run verify --strict locally: VERDICT: FAIL. The failures are the documented macOS-only Playwright environment issues (Settings shortcut never opens on Mac, and the port 9150 test server dying mid-run with page.goto timeouts and connection refused). The affected grid specs pass in isolation against a hand-started server. CI on Linux is the arbiter.

🤖 Generated with Claude Code

Co-Authored-By: Claude Fable 5.1 noreply@anthropic.com