chore: land the remaining low-severity items from the whole-project review

Phase 11 of PROJECT_REVIEW_PLAN.md: the themed cleanup pass over every
low-severity finding still open (2.2-2.3, 3.4-3.6, 4.3-4.7, 6.4-6.7,
7.1-7.3, 8.2-8.3, 9.1-9.4, and the under-documented decisions in §10/§11).

Behavioral fixes:
- Reassign duplicate job IDs in a hand-edited jobs.json instead of letting
  two jobs share one runtime, schedule entry, and SeedStats bucket.
- Disambiguate run-log file names that collide within the same second.
- Compute AvgDurationMS as DurationSumMS/TimedRunCount instead of an
  incremental integer mean, so it always matches the seeded-from-logs
  average instead of drifting from truncation error.
- Clean absolute paths in ResolveConfiguredPath so two spellings of the
  same jobs file do not trigger a spurious adoption.
- Report InstallDesktopIcon failures through ErrorOccurred instead of
  discarding them silently.
- Move settingsView's blocking AutostartStatus (PowerShell on Windows) off
  the UI thread.
- Give notify-timing.tsv its own extension so CleanupLogs no longer
  manages it as a run log.
- Replace the settingsView Save handler's second copy of validateConfig's
  rules with a bare parse, letting the Service's own error surface.

Cleanups:
- Delete collectActivity, the dead yaml tags on RunRecord, and the
  logArguments/LogArguments alias.
- Fold the two systemTrayRegistered/mainWindowHidden globals into one
  trayState instance Run owns and threads through Settings and the
  single-instance reveal path.
- Fix stale comments/docs: the frozen window-size restore claim, a
  reference to a renamed recordRun, README's "Pause all" and notification
  wording, the PowerShell quoting note for TESTS.md's coverage command,
  and scripts/test.bat's UTF-8 checkmarks under a non-UTF-8 code page.
- Document the single-instance fallback's consequence and the
  unauthenticated instance-channel port in STANDARDS.md; record the
  config-shim retirement plan in ROADMAP.md.

3.5, 7.3, and 9.4 turned out to already be fixed by earlier phases; no
change needed for those three.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

docs/ROADMAP.md

@@ -18,15 +18,35 @@ machine):** average **773 ms** per toast (695–874 ms), dominated by PowerShell
 cold start. Re-run the script when comparing after a native toast implementation.
 
 **App-side timing:** each failure notification appends one line to
-`logs/notify-timing.log` (`ms_after_run`, `ms_fyne_do`, `ms_send`,
+`logs/notify-timing.tsv` (`ms_after_run`, `ms_fyne_do`, `ms_send`,
 `ms_app_total`). These columns end when Fyne returns from `SendNotification`; OS
-toast latency is not included.
+toast latency is not included. The `.tsv` extension keeps it out of
+`runner.CleanupLogs`, which only manages `.log` files — this file is
+diagnostic instrumentation for this item, not job output, and should be
+removed (or unified with the run-log retention policy under its own knob) once
+the native-toast direction below lands and the timing data is no longer
+needed.
 
 **Direction:** add `src/platform/notify/` with a native Windows toast (WinRT or
 a maintained Go wrapper), used for failure notifications on Windows. Keep Fyne
 `SendNotification` on Linux (DBus / xdg-desktop-portal) unless profiling shows it
 needs the same treatment.
 
+### Retire the config compatibility shims
+
+Two read-only shims in `storage.loadOrCreateConfig` rewrite an old file into
+the current shape on the next save, so each becomes dead the moment a user's
+config has been saved once by a build that has it:
+
+- `Config.JobsDir` (pre-0.15, superseded by `Config.JobsFile`).
+- `Theme == "default"` (pre-1.0.1, superseded by `ThemeSystem`).
+
+Neither has an expiry. Remove both — the field, the migration branch, and
+`TestLoadOrCreateConfigMigratesJobsDir` /
+`TestLoadOrCreateConfigMigratesLegacyThemeDefault` — once a release has shipped
+long enough that a config file still carrying either old shape is not a
+realistic upgrade path GoSentry needs to support.
+
 ### Dynamic tray icon toggle
 
 Fyne exposes `SetSystemTrayIcon` and related APIs only at application startup.