fix(cloudflare): resolve D1 databases by name without total_pages - #3095

What does this PR do?

emdash migrate --d1 <name> could never resolve a name. databaseByName validated pagination with listInteger(value.total_pages, …), but the D1 list endpoint's result_info is { count, page, per_page, total_count } with no total_pages, so every lookup threw Cloudflare D1 database list total_pages is invalid. before looking at a single row. UUIDs and --wrangler-config were unaffected.

• Page count. When total_pages is absent, it is derived as ceil(total_count / per_page). When present it is validated as before. Everything downstream (the page loop, the cross-page consistency check, MAX_DATABASE_LIST_PAGES, the final seenCount === totalCount check) is unchanged and now runs on a value the endpoint actually implies.
• Substring matches (the issue's secondary note). name is a substring filter, and every row went through metadataDatabase before the exact-name filter. That throws for any non-production row, so once paging worked, a preview site-db-staging on the same page would still have failed the lookup for site-db. Rows are now filtered by exact name first, and only the matches are validated as deployment targets.

Closes #2840

Type of change

• Bug fix

Checklist

• I have read CONTRIBUTING.md
• pnpm typecheck passes: tsc --noEmit -p packages/cloudflare reports the same 7 errors on this branch and on main (unbuilt emdash workspace types), none in the touched file
• pnpm lint passes: oxlint --deny-warnings on the touched files
• pnpm test passes (or targeted tests for my change): see below
• pnpm format has been run: oxfmt
• I have added/updated tests for my changes (if applicable)
• User-visible strings in the admin UI are wrapped for translation: n/a
• I have added and reviewed the user-facing changeset
• New features link to an approved Discussion: n/a, bug fix
• I have included screenshots below if this PR changes the UI: n/a

AI-generated code disclosure

• This PR includes AI-generated code — model/tool: Claude Opus 5 (Claude Code)

Screenshots / test output

Not applicable (CLI). The test stub listApiResponse synthesized total_pages, which is why CI never saw this. The new cases in packages/cloudflare/tests/db/d1-migration-target.test.ts use a liveListApiResponse shaped like the endpoint the issue recorded:

• resolves a name from a single page;
• walks two pages derived from total_count: 2, per_page: 1;
• ignores a preview site-db-staging listed next to site-db;
• still reports No D1 database named site-db for an empty result.

main:  5 failed | 10 passed   # the 4 new cases ("total_pages is invalid") + 1 pre-existing
head:  1 failed | 14 passed   # only the pre-existing one

The one failure on both trees is uses the selected Wrangler environment and its own binding array, which asserts /project/wrangler.jsonc and gets a Windows path separator on this machine. CI on Linux should pass it. I did not run this against the live Cloudflare API.