Clipboard suggestion: mask based on content patterns (OTP/CC/JWT/seed/secret)

[dsremo]

Summary

isClipSensitive() currently only returns true when the target input field declares inputType=textPassword or the OS-side ClipDescription sensitivity flag is set. That leaves OTPs, credit-card numbers, BIP-39 seed phrases, JWTs, and PEM private keys visible in plaintext on the suggestion strip whenever the user is pasting into a normal text field (chat composer, email body, search bar) — which is the most common shoulder-surf risk in practice.

This PR extends isClipSensitive() to additionally inspect the clipboard content itself, returning true (and therefore masking the visible suggestion to ***...***) if the content matches any of:

Pattern	Matches
P_OTP	Standalone 4–8 digit run (whole-string match)
P_CREDIT_CARD	13–19 digit run with optional spaces/dashes
P_JWT	eyJ…\.<base64url>\.<base64url>
P_LONG_HEX	Hex string ≥ 32 chars (SHA-256, API tokens, hex-encoded keys)
P_SEED_PHRASE	12–24 lowercase 3–8 char words space-separated (BIP-39 style)
P_SECRET_KEYWORD	password, passwd, secret, api_key, access_token, bearer, private_key, ssh-rsa, ssh-ed25519, PEM private key block

Behavior

• The masking only affects the visible suggestion strip text. The actual paste still uses the real content via latinIME.onTextInput(content.toString()) — so functionality is unchanged for the user, they just don't see a 6-digit OTP rendered in 18pt next to whoever might be looking over their shoulder.
• 5000-char ceiling on the regex scan to avoid pathological clipboard payloads (e.g., full HTML pages on the clipboard) hitting the regex engine on every keystroke.
• Pattern list is intentionally conservative — false positives just mean "user sees *** instead of the value for ~3 minutes of clipboard freshness", false negatives mean the value is visible.

Files touched

• app/src/main/java/helium314/keyboard/latin/ClipboardHistoryManager.kt (+25 / −1)

Tested

Built and installed on Android 16 (HeliBoard_3.9-debug.apk). Verified manually with sample clipboard contents matching each pattern.

Notes

No new permissions. No new strings (the existing *-repeat path is reused). No settings — this is pure defense-in-depth on an existing privacy-sensitive code path. If you'd prefer this gated behind a setting, happy to add one.