Resolve SMB workspace follow-up feedback

[bifrost0x]

Summary

• treat a confirmed cancellation acknowledgement as terminal and keep SFTP browsing responsive by separating transfer channels from control operations
• make same-source moves visible and report failed, partial, and cancelled upload batches accurately
• simplify the SMB recovery-save explanation, remember consent per connection, and document TrueNAS/Active Directory UPN usernames
• restore embedded file toolbar actions after returning from the full file manager
• update translations, cache versions, documentation, and regression coverage

Follow-up to discussion #99 and PR #149.

Testing

• Python suite: 2185 passed, 29 skipped; all 4 loopback/socket tests also passed outside the sandbox
• JavaScript suite: 32 passed
• Playwright: 27 relevant file-workspace, SMB, and session-workspace tests passed
• ESLint: passed
• git diff --check: passed