[denson9874]

Requested by Daryl Denson

A review of the merged PRs #29–#32 found four problems. This fixes them before they ship in 4.0.0.

Before:

• Changing the system language left app names and the drawer's A–Z letters in the old language. This came from Stop reloading the whole launcher model on every recreate #30.
• While you typed, web suggestions, contacts, files and settings disappeared and came back 100–1000 ms later on every keystroke, so rows jumped under your finger. This came from Pixel-style drawer search: instant results, pill stays visible, calculator on #32.
• With no app match, pressing Enter before web suggestions arrived opened a Play Store search. This came from Pixel-style drawer search: instant results, pill stays visible, calculator on #32.
• With the calculator now on by default, typing e, pi or a plain number like 2024 showed a calculator row, and that row became the Enter target. This came from Pixel-style drawer search: instant results, pill stays visible, calculator on #32.

After:

• A language change reloads the launcher, so names and section letters switch right away. This also covers changing only a secondary language.
• Each section keeps the previous query's rows until its provider answers the new query, so rows no longer jump. Clearing the box, pressing Back or closing search starts the next search fresh.
• Enter searches the web instead of opening the Play Store. The row order is unchanged.
• The calculator answers only real calculations, such as 12*7, sqrt(16) or 2*pi. sqrt() is new.

How:

• InvariantDeviceProfile.toModelState() now includes the locale list, so the existing locale-change path runs refreshAndReloadLauncher.
• A new SeededProviderResults seeds each provider with its last answer from the same typing session.
• LawnchairLocalSearchAlgorithm ends the session on cancel(true) and on zero state, using a session counter and a lock around the job launch. A search queued just before Back therefore can't deliver results or seeds into the next session.
• AllAppsSearchInput also ends the session when Back clears a query.
• setFirstItemQuickLaunch skips the Play Store row while a web-search row is shown.
• CalculatorSearchProvider needs a digit and an operator or a function call before it shows a result.

Testing:

• Unit tests: 208/208 pass, and all 127 ci/tests pass. New tests: InvariantDeviceProfileLocaleTest, SeededProviderResultsTest, SearchQuickLaunchTargetTest and CalculatorSearchProviderTest. Each one failed before its fix.
• Emulator (Android 17 QPR2 AVD):
  • rows stay in place from wea to weat and on Backspace, measured frame by frame
  • calculator accepts and rejects the right inputs
  • Enter opens Chrome, never the Play Store
  • no old rows after Back
  • a rapid type-then-Back stress run
  • switching to German reloads the drawer with German names and letters
  • no launcher crash
• Reviews: two independent reviews for each fix, plus a review of how they fit together.

Known limits and follow-ups (not changed here):

• Enter pressed within a few ms of the last letter does nothing. It never opens old results.
• The Search on Google row can show the Play Store icon for about 2 frames after a keystroke.
• Blank cards can appear for about 200 ms when a new search first shows results.
• A hardware Enter key can start the web search twice. This is older behavior.
• After the language-change reload, some drawer icons lose their accessibility description. This is being checked separately.

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