Design: search results draw §5's row and empty state, and .no-hits leaves §5d #4103

A search with no hits now draws §5's empty() in place of .no-hits, and .no-hits is gone from the stylesheet and from the search bullet in docs/DESIGN.md §5d.

• Empty state: each section's "No app or repository matches", "No issue or pull request matches" and "No line of code matches" now go through empty(), still with that section's icon (src/web/pages/search.ts). The .no-hits rule leaves src/web/style/content.ts in the same commit that strikes the name from §5d. The bullet's other classes stay.
• Row order: repository and issue results already used row(), with the outcome first and where and who after it. I left them as they were, so the row-order test is untouched.
• Code hits: I did not convert them. codeHitRow is still hand-written markup, because test/search-more-code.test.ts and test/web-code.test.ts match its class="row code-hit" and code-line markup, and the DESIGN.md §5 table lists .code-hit as its own component. Converting it would mean changing those tests.
• Test: a new test in test/search-more-code.test.ts finds no no-hits on a search with no hits, and finds the three empty-state sentences and the empty-title class.
• Checks: bun test test/search and test/design-lint.test.ts pass (43 tests), as does test/web-code.test.ts. bun scripts/design-lint.ts reports nothing to fix. bun x tsc --noEmit is clean after bun install.
• Not run: the full bun test, which the forge's check runs on the push.

To try it, open /search?q=qqqxnothingmatchesqqq. Each of the three sections shows the dashed-border empty card with its icon.

Closes #4081

A search with no hits now draws §5's empty() in place of .no-hits, and .no-hits is gone from the stylesheet and from the search bullet in docs/DESIGN.md §5d.

• Empty state: each section's "No app or repository matches", "No issue or pull request matches" and "No line of code matches" now go through empty(), still with that section's icon (src/web/pages/search.ts). The .no-hits rule leaves src/web/style/content.ts in the same commit that strikes the name from §5d. The bullet's other classes stay.
• Row order: repository and issue results already used row(), with the outcome first and where and who after it. I left them as they were, so the row-order test is untouched.
• Code hits: I did not convert them. codeHitRow is still hand-written markup, because test/search-more-code.test.ts and test/web-code.test.ts match its class="row code-hit" and code-line markup, and the DESIGN.md §5 table lists .code-hit as its own component. Converting it would mean changing those tests.
• Test: a new test in test/search-more-code.test.ts finds no no-hits on a search with no hits, and finds the three empty-state sentences and the empty-title class.
• Checks: bun test test/search and test/design-lint.test.ts pass (43 tests), as does test/web-code.test.ts. bun scripts/design-lint.ts reports nothing to fix. bun x tsc --noEmit is clean after bun install.
• Not run: the full bun test, which the forge's check runs on the push.

To try it, open /search?q=qqqxnothingmatchesqqq. Each of the three sections shows the dashed-border empty card with its icon.

I merged main into the branch, resolved both conflicts, and pushed. I didn't wait for the full bun test run, which was still going after several minutes. I ran only the three design suites (design-audit, design-lint and design-map), and all 23 tests pass. tsc --noEmit printed no errors. The forge's check will run the full suite on this push.

• docs/DESIGN.md: main had already moved the client-list and claim-link classes out of the search-results line. I kept that, and this branch's removal of .no-hits from the list.
• src/web/style/content.ts: I dropped both sides' blocks. The .forges-sent and .claim-link-box rules are gone, as on main. The .no-hits rule is gone too, since this branch draws that state with the design system's classes.