What Changed

• Added a My PRs tab to the existing My Work tab strip instead of rendering it as a separate section.
• Populates My PRs from PRs authored by the logged-in GitHub user.
• Filters merged PRs out of My PRs so completed work does not stay visible there.
• Removes authored PRs from the other My Work lanes when they appear in My PRs, avoiding duplicates between My PRs, Needs me, mentions, waiting, and the other lanes.
• Makes My PRs the default tab when the user has authored, unmerged PRs; otherwise falls back to Needs me.
• Restyled My PRs rows to match the existing My Work row treatment used by Needs me.
• Added a small helper for My PR filtering/counting and a focused GitHub Work test covering author filtering, merged exclusion, status counts, and dedupe keys.

Repro Steps

Before this change:

1. Connect GitHub as a user with cached PRs in Fallback.
2. Open GitHub.com -> My Work.
3. Notice there is no first-class My PRs lane in the My Work tab strip.
4. Authored PRs can appear mixed into other work lanes such as Needs me or mentions.
5. Merged authored PRs can still be included in the PR-oriented view.

After this change:

1. Connect GitHub as a user with authored, unmerged PRs.
2. Open GitHub.com -> My Work.
3. Confirm My PRs is selected by default.
4. Confirm the rows in My PRs visually match the existing My Work row styling.
5. Confirm those same authored PRs do not also appear in Needs me, mentions, waiting, or other lanes.
6. Confirm merged PRs are not shown in My PRs.
7. Use an account/cache with no authored, unmerged PRs and reopen My Work.
8. Confirm the default selection falls back to Needs me.

Verification

• pnpm beta:check