bugs(C3): silent-failure P3 batch from the 2026-09-25 hunt #1250

Ten P3 silent failures from the read-only C3 hunt. The full table and file:line references are in temp/quality-loop/hunt-c3.md (rows 6–15). They are not yet verified by the loop; split any row out when it is picked up.

• 6. Provider enable/disable (ProviderEnablementRow.tsx:17-36) has no catch. Main's setupState cache is mutated before the write.
• 7. Pasting an image into a non-Claude composer does nothing, with no "provider doesn't take images" message (useClaudeImagePaste.ts:100).
• 8. A provider switch drops draft images without disclosing it (session.ts:1500-1506).
• 9. Copy Last Response reports success even when clipboard.writeText rejects (paneCommands.ts:464-465).
• 10. CLI update "View log" ignores the error string shell.openPath returns (ipc/cliUpdates.ts:69-78).
• 11. A git timeout reads as "clean" or "not a git repository" (ipc/git.ts:130-133).
• 12. A failed older-history load just stops the spinner (history.ts:249-252).
• 13. Setting the CLI auto-update behaviour has no rejection handler (cli-updates/store.ts:122-126).
• 14. The skills and conventions recovery banner's Reveal/Reset ignore failures.
• 15. An update-channel write failure is swallowed, and the channel reverts after a restart (main/index.ts:462).