feat(settings): ask an optional reason when deleting the account

[Armin1019]

Summary

Asks users why they delete their account, so product can see why people leave. The question is optional and adds no required tap (Apple 5.1.1(v)).

• Delete modal (Settings → Account → Delete Account): one optional single-choice question with 7 reasons, plus a 200-character text box when "Other" is picked. Tapping the chosen reason again clears it. The order is shuffled each time the modal opens, with "Other" always last, so the first option isn't over-picked.
• Analytics: new account_deleted event with a fixed reason key (skipped when nothing is chosen) and other_text only for "Other". It fires just before the delete request and is flushed, so it leaves while the user is still identified (logout resets PostHog right after). Wrapped in try/catch, so analytics can never block the deletion.
• Wording approved by Freya, with her three changes applied (softer title, new privacy reason, "no longer need this kind of app"). Approval screenshot below.
• No backend change.

Verified: Android emulator on staging. Reasons show, select and clear; "Other" opens the text box; reopening the modal starts empty with a new order. Deleted a throwaway account with a reason → account deleted and logged out. Captured payload (PostHog is off outside production, so this is a temporary local log, already removed):

09:14:05.990  account_deleted {"reason":"no_longer_needed","otherText":""}
09:14:09.841  clear credentials successfully   ← logout, after the event

The production check (an account_deleted event seen in PostHog) happens after release, per the PBI.

Release note

Deleting your account now includes a short, optional question about why you're leaving, so we can keep improving Blotz.

Status:

• User-facing — announce it
• Beta / partial — announce, but tagged as beta
• Hidden in production (feature-flagged / not enabled for users) — don't announce
• Internal only (refactor / infra / tests / CI / deps) — don't announce

[github-actions]

Test Results

148 tests   148 ✅  9s ⏱️
  1 suites    0 💤
  1 files      0 ❌

Results for commit 045cb2a.

♻️ This comment has been updated with latest results.

[github-actions]

Package	Line Rate	Branch Rate	Complexity	Health
BlotzTask	4%	36%	2969	❌
BlotzTask	4%	36%	2969	❌
Summary	4% (5190 / 117310)	36% (1138 / 3178)	5938	❌