revert: remove demo-only contract kanban and competitor module (#532 follow-up)

[yinlianghui]

Description

#532's squash merge carried two feature commits in alongside the license fix: the contract status kanban board and the competitor management module. Both were built as recording aids for a demo video series and were not meant to land upstream. This PR reverts them; the dashboard dateRange fix from the same squash (#499) stays.

Type of Change

• Breaking change (fix or feature that would cause existing functionality to not work as expected) — removes the crm_competitor object and the multi-value crm_competitors lookup on opportunities

Related Issues

Related to #532

Changes Made

• Revert feat(competitor): add competitor management module: removes the crm_competitor object, its two list views, Sales nav entry, seed records, and translations (en/zh-CN/ja-JP/es-ES); the opportunity object returns to its previous hardcoded competitors select, and the opportunity form/detail page drop the lookup field.
• Revert feat(contract): add status kanban board view: removes the contract_board kanban from the contract views.
• Changeset added (minor).

Testing

• Unit tests pass — 89/89, identical to the main baseline (pnpm test)
• Linting passes — findings identical to main
• Build succeeds (pnpm build, pnpm typecheck clean)
• Manual verification — zero remaining references to crm_competitor / contract_board in src/

Checklist

• I have added a changeset (.changeset/remove-demo-only-features.md)
• I have performed a self-review of my own code
• New and existing unit tests pass locally with my changes

Additional Notes

Based on latest main (387d375, includes #505). The metadata guard tests in test/metadata-references.test.ts confirm no dangling references (nav, views, pages, translations) remain after the removal. The demonstrated state (all demo features, as shown in the video series) remains browsable at the fork tag demo-series-2026-07.

🤖 Generated with Claude Code

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