Android: Signature capture

Technical specification for signature capture in the PestControlOS Android app.

Behaviour

Screen: Dedicated signature capture screen (e.g. canvas or view for drawing). Used by Create Report, Action Forms, service agreements where signatures are required.
Output: Signatures saved as PNG files under app external storage (e.g. getExternalFilesDir() or equivalent). File path or content URI returned to calling activity/fragment.
Integration: Caller receives URI(s); can embed in generated PDF (iText) or attach to documents. Technician and customer signatures may be captured in sequence; each returns a URI.

PNG files stored in app-private external storage; not in Firestore. URIs passed in-memory or via Intent extras to report/PDF generation. No sync to Firebase unless the resulting PDF is uploaded.

Files are app-scoped; other apps cannot read without root or backup. When PDF is uploaded to Firebase Storage, access controlled by Storage rules.