docs: add auto-update implementation plan and rescope roadmap

Co-authored-by: Cursor <cursoragent@cursor.com>

docs/ROADMAP.md

@@ -7,37 +7,20 @@ Completed work is recorded in [CHANGELOG.md](CHANGELOG.md), not here.
 
 User-facing functionality that is not blocked on a framework or platform gap.
 
-### Update check from GitHub releases
+### Auto-update from GitHub releases
 
-Releases are published as GitHub Releases (tags like `v0.12.0`, built by
+Releases are published as GitHub Releases (tags like `v1.0.4`, built by
 `.github/workflows/release.yml`), but the app never tells the user a newer
-version exists — they have to check the releases page by hand.
+version exists — they have to open the releases page by hand.
 
-Add an update check that queries the GitHub Releases API
-(`GET /repos/mixeme/gosentry/releases/latest`) for the latest published tag,
-strips the leading `v`, and compares it against `app.Version`. When a newer
-version is available, surface it non-intrusively — an "Update available"
-line in Settings (next to the existing version/build info) with a hyperlink
-to the release page, not a modal on launch.
+Ship opt-in update checks and one-click install for the portable archives:
+semver compare against `app.Version`, signed downloads, replace the running
+executable, and restart. Settings shows status in the About section; no modal
+on launch.
 
-Design notes / open questions:
-
-- *Opt-in and offline-safe.* The check makes a network request, so it must be
-  off by default (or clearly consented) and never block startup. Failures
-  (offline, rate-limited, API change) should be silent — no error dialogs for a
-  best-effort convenience feature.
-- *Version comparison.* Compare semantic versions, not strings, so `0.12.0`
-  reads as newer than `0.9.0`. A tiny semver comparator in `app` (or a small
-  dependency) avoids lexical bugs.
-- *Where the check lives.* Keep it in the `app` layer behind the Service so the
-  UI only renders the result, and cache the last check so opening Settings
-  repeatedly does not spam the API (unauthenticated GitHub allows 60 req/h).
-- *Repo coordinates.* The primary remote is Gitea; the GitHub repo used for
-  releases is [`mixeme/gosentry`](https://github.com/mixeme/gosentry) and must
-  be wired in explicitly (constant or build-time value) rather than derived from
-  `origin`.
-- *No auto-download.* Scope is detection and notification only; installing the
-  update stays a manual click-through to the release page.
+Implementation is **design-first** (UI on a stub, then backend). Phases,
+security, and platform details live in
+[AUTO_UPDATE_PLAN.md](AUTO_UPDATE_PLAN.md).
 
 ### Import/export jobs as a cron table