feat: add edit sprint functionality and completed sprints section to project interactions

[pikann]

Summary

Previously, completed sprints disappeared from the sidebar entirely once closed, and sprint metadata (name, goal, start/due date) could only be set once when starting a sprint — there was no way to fix a typo or adjust dates afterward.

• Sidebar now shows a collapsible Completed Sprints section (collapsed by default) below the active sprints, so past sprints stay reachable instead of vanishing after completion.
• Sprint detail page gets a new Edit sprint action (next to Complete sprint, gated on sprints.write) that opens a modal to update the sprint's name, goal, start date, and due date — available regardless of sprint status, including completed sprints.
• Added the new UI strings to all 9 supported locales.

Changes

• apps/web/src/components/app-shell/app-sidebar.tsx — collapsible "Completed Sprints" list in the project sidebar, filtered from the existing sprints query.
• apps/web/src/routes/_authenticated/projects/$projectId/interactions/sprints/$sprintId.tsx — "Edit sprint" button + modal wired to the existing PATCH /projects/:projectId/sprints/:sprintId endpoint (no backend changes needed — it already supported updating these fields for any sprint status).
• apps/web/src/i18n/locales/*/{appShell,projects}.json — translated strings for interactions.completedSprints and layout.sprintDetail.editSprint(Modal).

Test plan

• tsc -b --noEmit passes
• biome check passes
• Manually verify: complete a sprint, confirm it appears under "Completed Sprints" in the sidebar and opens correctly
• Manually verify: edit name/goal/start/due date on an active, planned, and completed sprint, confirm changes persist and sidebar/detail view update

[pullfrog]

✅ No new issues found.

Reviewed changes

This PR adds two related project-interactions features across 20 files (18 of which are i18n locale additions):

• Edit sprint modal — apps/web/src/routes/_authenticated/projects/$projectId/interactions/sprints/$sprintId.tsx now lets users with sprints.write permission edit a sprint's name, goal, start date, and end date via a new inline modal backed by the existing updateSprint API.
• Completed sprints sidebar section — apps/web/src/components/app-shell/app-sidebar.tsx now renders a collapsible "Completed Sprints" section below active sprints, sorted by updated_at descending.
• i18n coverage — added interactions.completedSprints in appShell.json and layout.sprintDetail.editSprint / editSprintModal.* keys in projects.json for all supported locales.

The edit flow reuses the existing UpdateSprintPayload/updateSprint client, invalidates the correct query keys, and matches the date-conversion pattern already used by StartSprintModal. The completed-sprints list is scoped to users who can view sprints and mirrors the active-sprint item styling. No blocking issues.

  ^{｜ View workflow run ｜ Using Kimi K2 (free via Pullfrog for OSS) ｜ 𝕏}

[pullfrog]

✅ No new issues found.

Reviewed changes

The latest commit polishes the initial edit-sprint and completed-sprints work:

• Persisted completed-sprints collapse state — app-sidebar.tsx now stores the collapsed/expanded state per-project in localStorage (paca:sidebar-completed-sprints-collapsed:${projectId}), defaulting to collapsed and guarded against storage exceptions.
• Kept sprint counts fresh during task edits — interaction-layout.tsx now invalidates ["projects", projectId, "sprints"] after task status changes, creation, updates, and deletion so the Complete Sprint dialog's move-to-sprint suggestions reflect current incomplete-task counts.
• Added client-side date validation and error handling — the edit sprint modal validates that the due date is not before the start date (string comparison on YYYY-MM-DD is lexicographically correct), disables save while invalid or empty, surfaces a generic error message on API failure, and closes on Escape via a document-level listener that matches StartSprintModal.
• Added missing i18n strings — all 9 locales received editSprintModal.dateRangeError and editSprintModal.error.

Verified that the invalidated query keys exactly match sprintsQueryOptions / sprintQueryOptions. No blocking issues.

  ^{｜ View workflow run ｜ Using Kimi K2 (free via Pullfrog for OSS) ｜ 𝕏}