[Chore] Prepare 0.3.1 patch release notes

[roomote-roomote]

Opened on behalf of Matt Rubens. Follow up by mentioning @roomote-roomote, in the web UI, or in Slack.

Related issue

N/A — patch release notes for post-0.3.0 develop backlog (Slack request).

Why this PR exists

• A maintainer explicitly invited this PR in the linked issue or discussion
• I am a maintainer / this is internal Roomote work

What changed

Adds four patch changeset files for user-facing work that landed on develop after v0.3.0 and did not already have notes:

• Task history records linked PR merged/closed status for agents (patch, not minor)
• Visual-proof Slack auto-post is gated by SlackProofAutoPost
• Mobile task filter PR-repo labels left-align correctly
• GitHub app @mention matching requires word boundaries

Does not touch CHANGELOG.md or the root version — CI owns both on the Version PR.

Already-pending notes left alone (from #245 / #247, both patch; already on develop, so not in this PR’s file diff):

• Bedrock Mantle API key routing
• Vertex credential materialization before OpenCode

Branch is current with latest develop (includes docs GitHub link update #250).

Expected next version: 0.3.1

Highest pending bump level across all six changesets is patch (0.3.0 → 0.3.1).

Preview of ### Patch changes bullets for 0.3.1

• Route Amazon Bedrock API keys through the Mantle endpoint and clarify Mantle key setup in model settings.
• Materialize pasted Google Vertex service-account credentials before OpenCode starts so Vertex models work across worker paths without exposing credential JSON in provider errors.
• Task history records when a linked pull request is merged or closed as an out-of-band status message agents can resurface (GitHub, GitLab, Gitea, Bitbucket, and Azure DevOps), using provider-native PR references.
• Visual-proof auto-post to Slack is actually gated by the SlackProofAutoPost experimental flag; when the flag is off, proof is no longer auto-posted and agents must share uploaded screenshots through explicit chat replies.
• Task filter PR-repo labels left-align correctly in the mobile filter sheet instead of sitting awkwardly centered.
• GitHub app @mention detection requires word boundaries so longer lookalike logins and emails containing the configured slug no longer falsely trigger agent replies.

Merging this PR makes CI open or refresh the Release Roomote 0.3.1 Version PR on changeset-release/develop, which is what bumps the product version and updates CHANGELOG.md.

Intentionally omitted from notes

• Simplify models provider documentation #248 docs-only simplification
• Point docs GitHub links to main #250 docs GitHub links to main
• [Improve] Skip “CI is passing” padding in PR review notifications #244 CI-padding wording (already reflected in the published 0.3.0 changelog section)
• [Refactor] Extract OpenCode stall and steer-pickup watchdogs from harness #240 pure harness refactor
• [Chore] Retire legacy internal bot naming #237 legacy-bot naming chore

How it was tested

Reviewed v0.3.0..origin/develop first-parent history, pending .changeset/*.md, and PR bodies for user-facing impact. No runtime code changes.

Impact

Once merged and the Version PR ships, product version becomes 0.3.1 with the six patch bullets above (four added here + two already pending on develop).

Checklist

• The PR title follows the repo convention: [Fix], [Feat], [Improve], [Refactor], [Docs], or [Chore] followed by a user-facing description
• This PR is small and scoped to one change
• pnpm lint and pnpm check-types pass locally
• I added tests or included a clear manual validation note above
• I removed secrets, tokens, private keys, and customer data from code, logs, and screenshots
• If this change should appear in the changelog, I ran pnpm changeset

[roomote-roomote]

No new code issues. See task

The task-history changeset was intentionally set back from minor to patch, so the PR is now self-consistent at 0.3.1 — the title, body, and changeset all agree again.

Heads-up (non-blocking): the source work (#243) shipped as a [Feat], which .changeset/README.md classifies as minor (new backward-compatible capability). Keeping this note at patch under-classifies it against that convention. It reads as a deliberate scope choice for 0.3.1, and the PR has already merged, so this is informational only.

• .changeset/task-history-pr-status.md:2 — Settled: intentionally reverted to patch in 52d4aa8, keeping the release at 0.3.1 and making the PR title/body/changeset consistent. Note: [Feat] Add merged and closed PR status to task history #243 was a [Feat], which .changeset/README.md maps to minor; patch is a deliberate under-classification for this release.

_{Reviewed 52d4aa8}