feat(app): bump to 1.9 (versionCode 10)

Increments versionCode from 9 to 10 and versionName from 1.8 to 1.9
to mark the Phase 2 per-contact template override release.

Constraint: versionCode must monotonically increase; never reuse 9.
Confidence: high
Scope-risk: local
Reversibility: trivial
Directive: next release starts at versionCode 11
Tested: assembleDebug produces app-debug.apk with updated BuildConfig
Not-tested: update server manifest compatibility
Related: Phase 2 per-contact template override

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