Gengchou: baixar versions anteriors

The daily update check now raises a silent balloon once per version. Clicking it asks whether to update. The detail popup footer shows the waiting version while an update is outstanding and that line is clickable. A remembered offer that is not newer than the running build is treated as up to date. A failed automatic check does not clear the last successful offer.

Fixes a group of failures that gave no sign they had happened. A panic on a background thread left the usage frozen for as long as the app stayed open. A settings file that could not be read or parsed was replaced by defaults within seconds; the original is now kept as settings.json.corrupt and reported once. Claude and Codex recorded an empty quota response as a successful refresh and erased the numbers, and now keep the last good values instead. A second signed-in Windows account could not start Gengchou at all, because the single-instance guard was machine-wide while settings are per user; it is now scoped to the data directory it protects. An Explorer restart could stop monitoring for good in the degraded startup path. A credential probe that wrote more than the pipe buffer holds was reported as a provider that never answered. The updater is also hardened, confirming that its target is this installation before replacing or starting it, checking the download's version and not only its hash, and validating its working directory before downloading into it.

Fixes every informational tray balloon, which Windows accepted and then silently dropped from v2.4.1 onward, so quota window reset reminders never appeared. Stops the detection sweep from reading the local credentials of a provider whose access was revoked, and repairs the periodic sweep, which had never run. Fixes a profile whose only authorised provider is Grok never polling at all. Reports a credential that exists but cannot be used as an authentication failure for Codex, Antigravity and Grok instead of showing it as not detected. An upgraded setting that only records allow=false is now marked as needing review rather than guessed to be a revocation, and nothing is read for it until you choose Allow access or Keep closed.

Adds Grok as a fourth provider, reading the session that grok login already stored and the billing period the provider itself reports. Fixes credential probes inside WSL for every provider, where the probe script was handed to the distribution login shell and re-parsed, so a credential that existed only inside WSL was reported as absent. Also persists Grok in the usage cache and stops an unknown provider name from rejecting the whole settings file.

Improves reliability by separating unavailable WSL probes from credential failures, rotating diagnostics while running, serializing settings and cache writes, limiting JSON responses to 4 MiB, and enforcing release ancestry.

Reserves the Windows warning glyph for notifications that require action. Routine provider detection, quota reset, and Claude Code update notifications use the Gengchou app icon and remain silent. Adds current provider integration and OpenCode Go engineering notes.

Replaces the per-provider first-run prompts with a single permission prompt covering every provider, then detects and shows only the providers signed in on this machine. Existing installations keep their current selection and are never prompted again. Adds a "Not detected" state distinct from "Authentication failed", periodic and on-demand provider detection, and reads Codex and Antigravity credentials from already-running WSL distributions.

Fixes the first-run permission prompt so it appears after an app surface is visible, remains minimizable, and continues to default to No without reading credentials before authorization.