fix(web): contain dialog content and localize agent fork dialog

[Yevanchen]

Fill what changed. Use N/A for irrelevant or maintainer-only items. See CONTRIBUTING.md for branch, CLA, generated file, and CI rules.

Summary

• Contain every dialog's content inside the dialog: DialogContent's grid had no column template, so the implicit auto column floored at the widest child's min-content contribution (nowrap truncate targets in AgentAssignField, the field-sizing-content composer Textarea). The New Thread dialog's assign-to control and composer extended ~760px past the dialog edge and pushed Dispatch off-screen. Fixed at the shared boundary with grid-cols-[minmax(0,1fr)] — no viewport-specific fixed widths.
• Localize the Change Agent type (fork) dialog: it rendered raw keys (AGENTLIFECYCLE.KINDCATTLETAGLINE, agentLifecycle.forkCarried*, forkAddedSandbox, forkStays*, assistantSandboxState) and an uninterpolated Fork as {{kind}} button. The kind chips now reuse the canonical agent.assistantAgent / agent.taskAgent labels and agent.kind*Tagline taglines, the seven missing agentLifecycle entries were added to en / zh-CN / zh-TW / ja, and the confirm label passes the kind variable the forkAs catalog entry expects.
• Regression coverage in apps/web/tests/reported-i18n-layout-regressions.test.ts: every key referenced by the fork dialog must resolve in every locale, the forkAs call must pass {{kind}}, and the shared dialog grid must keep its shrinkable column.

Why

• Two reported production regressions: Runs → New thread overflows horizontally with a published Agent that has a long description (Dispatch can leave the viewport), and the fork dialog shows raw i18n keys/placeholders in both fork directions.

Verification

• Commands:
  • just test-package @mosoo/web — 236 pass / 0 fail
  • just test-file apps/web/tests/reported-i18n-layout-regressions.test.ts and apps/web/tests/i18n-catalog-parity.test.ts — pass
  • just tc-package @mosoo/web, just fmt-check, git diff --check, just commit-check — pass
• Manual steps: local browser acceptance via Playwright against just dev with the loopback @mosoo.ai login. Before fix at 1440×900 the dialog's right edge was at 1100px while the assign control / composer / Dispatch measured 1840 / 1857 / 1872px (Dispatch outside the 1440px viewport, expand toggle unclickable). After fix: 1047 / 1064 / 1079px, all inside the dialog; verified in normal, expanded, 1024×800, and 390×844 layouts, with long descriptions truncating without changing dialog width. Fork dialog audited in both directions (Assistant → Task and Task → Assistant) in en, zh-CN, zh-TW, ja: zero raw namespace.key or {{var}} tokens; before/after screenshots attached on the tracking issue.
• Not run: just check full gate stops on 12 pre-existing apps/driver ACP/watchdog test failures that also fail on clean main with this change stashed (environment-dependent process-supervision fixtures); fmt, doc links, lint, tc, and GraphQL freshness stages pass.

Impact

• User/API/contract changes: user-visible only — dialog layout containment (all dialogs share DialogContent) and fork dialog copy in four locales. No API or contract changes.
• Generated files / GraphQL / DB / lockfile: none.
• Env or config changes: none.
• Risk and rollback: grid-cols-[minmax(0,1fr)] affects every dialog; dialogs always had definite widths (w-full + max-w-*), so the column template only stops children from outgrowing the popup. Revert the single commit to roll back.

Review

• Closest review areas: apps/web/src/shared/ui/dialog.tsx (shared grid template), apps/web/src/routes/agent/lifecycle/kind-fork-dialog.tsx (key reuse + {{kind}} interpolation), translation catalogs.
• Known trade-offs: the fork dialog now shares kind labels/taglines with the kind selector (agent.* keys) instead of carrying duplicate agentLifecycle.kind*Tagline copy — one canonical name per concept.