fix(newsletter): stop dismissal re-pop loop and add DB write observability

[peppescg]

What & why

First step of #2321. The newsletter modal re-pops and won't stay dismissed because the dismissal is never persisted when the SQLite write fails silently — users then submit junk emails to make it go away (the "newsletter spam"). This PR stops the worst symptom and, crucially, adds the telemetry we're missing so we can measure how often this actually happens before investing in deeper fixes.

It deliberately does not change the read-only DB behavior or add filesystem mitigations — those are follow-ups (PR2/PR3 in #2321), gated on the data this PR collects.

Changes

1. Stop the in-session re-pop loop (only when persistence fails)

• setNewsletterDismissedAt now returns whether the dismissal was actually persisted (false = read-only DB or a failed write).
• The renderer suppresses the modal for the rest of the session only when it wasn't persisted. When the write succeeds, behaviour is unchanged (the stored state handles suppression). This kills the "dismiss → invalidate → refetch empty dismissedAt → re-show" loop observed in Sentry (one install dismissed the modal 9 times in 5 minutes).

2. Observe DB write failures in Sentry, split by bucket

• Bucket A (read-only DB: on-disk schema newer than the app) — captured in the migrator with applied vs known schema. This path is currently completely silent (not even a local log).
• Bucket B (the write threw) — captured in the settings writer with the native SQLITE_* code.
• os.name / release are attached automatically by @sentry/electron, so we can see which OS/versions are affected.

Testing

• pnpm type-check ✅, eslint on changed files ✅
• main/src/tests/newsletter.test.ts ✅ (added coverage for the new boolean contract: persisted/read-only/throws)
• main/src/db/__tests__ (migrator + writers) ✅
• Added a renderer regression test (modal stays gone when the dismissal can't be persisted). Renderer (jsdom-via-Electron) tests don't run in my local sandbox; they'll run in CI.

Refs #2321

[Copilot]

Pull request overview

This PR addresses the newsletter modal “dismiss → re-show” loop when the dismissal cannot be persisted to SQLite, and adds main-process Sentry telemetry to observe (a) “DB forced read-only due to schema newer than app” and (b) “SQLite write threw” failures.

Changes:

• Changed the dismissal IPC contract so setNewsletterDismissedAt returns boolean indicating whether the dismissal was persisted.
• Updated the renderer modal to suppress re-showing within the same session when persistence fails, plus added a regression test for this behavior.
• Added DB write failure telemetry (Bucket A via migrator; Bucket B via settings writer) with schema / SQLite code context.

Reviewed changes

Copilot reviewed 9 out of 9 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
renderer/src/common/mocks/electronAPI.ts	Updates mock return type for setNewsletterDismissedAt to boolean.
renderer/src/common/components/newsletter-modal.tsx	Uses persisted/not-persisted result to avoid in-session re-pop loop.
renderer/src/common/components/tests/newsletter-modal.test.tsx	Adds regression coverage for “cannot persist dismissal” session behavior.
preload/src/api/app.ts	Updates preload API typing for setNewsletterDismissedAt to return Promise<boolean>.
main/src/tests/newsletter.test.ts	Updates unit tests for new boolean contract and read-only / throw scenarios.
main/src/newsletter.ts	Makes setNewsletterDismissedAt return persisted status; skips on read-only.
main/src/db/writers/settings-writer.ts	Captures and reports thrown write failures (Bucket B) before rethrowing.
main/src/db/telemetry.ts	Adds captureDbReadOnly and captureDbWriteFailure Sentry helpers.
main/src/db/migrator.ts	Captures schema-newer read-only condition (Bucket A) when disabling writes.