Correct keyboard runtime defects found during the v4.2.0 integration review

[AsafMah]

Describe the bug
An independent full fork/upstream-delta review of v4.2.0 merge 0ab4172f found concrete incoming runtime defects, plus two retained keyboard-state bugs. They must be corrected before the integrated build is treated as ready for installation. This is regression repair, not a redesign or another gesture experiment.

To Reproduce
The correction work tracks separate fixtures for each item below: isolated sound ZIPs, password/web-password EditorInfo, controlled camera-provider futures and executor errors, delayed OCR recognition, math expressions and exact cursor suffixes, touchpad MotionEvents, and activity recreation. No destructive fixture may operate outside a temporary test context.

Expected behavior

• K1: sound-pack manifest IDs/destinations cannot escape or delete the pack root.
• K2: inline math never reads/displays password text or stores protected-session history.
• K3: stopping/releasing OCR invalidates delayed camera startup.
• K4: replacing/detaching input views releases their owned camera resources.
• K5: capture result/error UI is delivered on Main, never the camera executor.
• K6: dictation does not silently change global software microphone mute.
• K7: cancelled/stale OCR initialization and recognition cannot reopen UI or modify clipboard/editor.
• K8: math acceptance replaces only the verified original expression range, preserving delimiters/whitespace.
• K9: unary negation respects operator precedence.
• K10: percentages respect surrounding operator semantics.
• K11: final finger-up preserves a valid pending two-finger tap decision.
• K12: clipboard draft text and selection survive activity recreation.
• K13: generated sound manifests preserve nested relative audio paths.
• K14: failed OCR plugin replacement preserves the working installation.
• K15: screenshot refresh recognizes visible floating keyboards without background polling while hidden.
• K16: OCR transitions clear both text-edit and persistent-selection state.
• K17: the existing OCR auto-insert preference works only for a still-current request/editor.
• K18: the existing flash-persistence preference restores the choice while hardware is off after closure.
• K19: local and downloaded OCR plugin imports perform heavy work off Main.
  Every item requires a failing-before regression and verified correction. Preserve the four flavors, network/addon boundaries, current defaults and all unrelated upstream functionality.

Screenshots
N/A — code review with targeted runtime fixtures; no device camera/native-plugin validation is claimed.

App version & Flavor
LeanTypeDual v4.2.0 integration 0ab4172f; correction work based on 4273800bf and later reviewed integration commits. K11/K12 predate this merge; other items are incoming or merge-integration defects. Applies where the corresponding feature is available.

Device Info

• Model: no physical-device result claimed by this review.
• OS version: controlled Robolectric scenarios; OEM/camera/plugin behavior remains a separate verification boundary.

[AsafMah]

Integration update: #155 includes the already-completed runtime corrections alongside current LeanBitLab upstream. The old four-flavor retention requirement is superseded by the maintainer-authorized three-flavor/plugin alignment. Installed EXP received initial user feedback "feels ok"; that is not exhaustive camera/native-plugin validation. This is packaging the existing baseline, not starting another broad inherited-feature repair pass.