Fix Android lint baseline warnings

[powerje]

Summary

• Fix 1346 Android lint warnings across 17 commits, reducing baseline from 1869 to 523 issues (72% reduction)
• Categories fully resolved: MissingSuperCall, DrawAllocation, HandlerLeak, ResourceType, DiscouragedApi, InflateParams, ObsoleteSdkInt, SwitchIntDef, ManifestOrder, ScopedStorage, ApplySharedPref, DefaultLocale, SuspiciousIndentation, SdCardPath, SourceLockedOrientationActivity, OldTargetApi, UseRequiresApi
• Categories significantly reduced: RtlHardcoded (344→5), HardcodedText (460→14), SetTextI18n (115→15), SpUsage (83→0), PxUsage (45→0), SmallSp (8→0), ClickableViewAccessibility (9→0), InefficientWeight (9→0), DisableBaselineAlignment (5→0), RtlSymmetry (16→0)
• Extract 170+ string resources from hardcoded XML text
• Replace anonymous Handler classes with static inner classes to prevent memory leaks
• Move object allocations out of onDraw() methods into preallocated fields
• Add accessibility content descriptions to ImageButton/ImageView elements
• Replace hardcoded /sdcard/ paths with Environment.getExternalStorageDirectory()

Remaining baseline (523 issues)

Mostly layout-level issues requiring structural changes: ObsoleteLayoutParam (122), Autofill (81), LabelFor (55), ButtonStyle (50), ContentDescription (46), TextFields (33), UselessParent (32)