Honour the export and delete promises for everything the app now stores

[mapgie]

The in-app promises are explicit: the privacy disclaimer says you can "export a copy of all your data" and delete everything via Settings, Data, Delete All Data; the backup dialog says a full backup is for "transferring to a new phone". An audit of the export builder, the importer, and the delete paths against the current schema (post logging redesign) and the full preferences list found gaps on all three surfaces. This PR closes them.

What was broken

Export/restore lost data

• The groups table (added in the redesign) was never exported: a restore lost all grouping and group membership, and any category set to inherit its group's colour rendered neutral grey afterwards.
• loggedAt was not exported and the importer called saveLog with defaults, so time-tracked history lost every timestamp and a day with several allow-multiple entries collapsed to its last entry.
• Colour profiles dropped their lightBackgroundArgb/darkBackgroundArgb columns.
• Seven settings were missing from the backup, including the period gap tolerance (which shapes episode derivation on import), period tracking on/off, and custom theme backgrounds/name.

Deletion left data behind

• User-named groups (names like "Pain" can be sensitive) survived both "Delete All Data" and "Reset category settings".
• The saved pregnancy date survived "Delete All Data".
• Exported JSON files accumulated in the app cache indefinitely: the filename embeds the date, so the code's "overwritten on every export" comment was only true within a single day.

What changed

• Full backup format v4 to v5: adds a groups array and a per-category groupName (name-matched on import, since row ids change across a restore; backups without the key leave existing filing untouched), per-log loggedAt, colour-profile background columns, and the missing settings. Old backups still import; old app versions ignore the new keys.
• Importer: new importGroups (replace mode clears groups first, never their member categories) runs before category config; log import now passes allowMultiple and loggedAt through to saveLog; periodGapToleranceDays is range-validated (0..3) before applying.
• Deletion: "Reset category settings" also deletes groups (members unfiled first; two additive DAO queries). "Delete All Data" also clears the pregnancy date and the export cache, and its dialog says so.
• Export cache: every export clears the directory before writing, and DataExporter.clearExportCache is shared with the delete path.
• Copy: backup description now mentions groups; both delete dialogs updated to match behaviour; fixed three pre-existing en/em dashes in user-facing strings in the touched dialogs (custom range separator, Merge/Replace descriptions).

Verification

• a11y_check.py clean, wcag_check.py passes, semantics-import sweep clean, changelog fragment validates (minor).
• Every new symbol call checked against its declaration (setter signatures, saveLog's allowMultiple/loggedAt parameters, ColorProfile constructor, group repository methods).
• LESSONS.md records the transferable lesson: a "keep this in sync" comment on the delete method did not survive the next table; schema/preference PRs need an explicit export/import/delete sweep.

🤖 Generated with Claude Code

https://claude.ai/code/session_01PZJLynVBkgLtehJFXffnfg

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