refactor: establish explicit source ownership

[jasonhedman]

Summary

• promote the Eve agent and Next route tree to first-class root owners
• move browser support to web, persistence and auth to db, and stable cross-owner contracts to shared
• replace ambiguous @/* imports with explicit owner aliases
• enforce production dependency direction with a repository-owned Oxlint rule

No product behavior changes are intended; this PR is focused on file ownership, import paths, configuration, and architectural lint enforcement.

Validation

• pnpm types:generate
• pnpm check (79 test files, 683 tests)
• pnpm build (safe local placeholder environment)
• pnpm exec eve info (0 diagnostics)