[codex] honor homepage search query

[Sean-Kenneth-Doherty]

Summary

• initialize the project search box from the homepage q query parameter
• let the existing client-side filter apply immediately on page load
• show an accessible no-results status message when a query or filter hides every project
• make the published structured search URL return filtered project results instead of ignoring the query

Refs #348
Refs #501

Validation

• GITHUB_TOKEN=$(gh auth token) pnpm build
• executed the generated module script against a fake DOM: ?q=react seeds the input and filters 152 cards to 17 visible with the no-results message hidden; a no-match query filters 152 cards to 0 visible and shows the no-results message
• confirmed generated dist/index.html includes role="status" and aria-live="polite" on the no-results message
• git diff --check

[Sean-Kenneth-Doherty]

Validated this head in a detached scratch worktree (967ebae42fe60e70fd9783b58cc17db4c2a8e87d).

Commands/checks run:

GITHUB_TOKEN=$(gh auth token) pnpm build
node --input-type=module   # exercised the ProjectList script against a fake DOM
git diff --check

Result: pnpm build completed successfully. The fake-DOM check loaded the same 152 projects used by the page: ?q=react seeded the search input and filtered the list to 17 visible cards with the no-results message hidden; a no-match query filtered to 0 visible cards and made the no-results message visible. git diff --check was clean.

[Sean-Kenneth-Doherty]

Fresh validation against the current PR head (833bd61):

• GITHUB_TOKEN=$(gh auth token) pnpm build -> Astro build succeeded, 2 pages
• executed the generated ProjectList module script against a fake DOM loaded with the 152 current projects
• ?q=react seeded the search input, filtered to 17 visible cards, and kept the no-results message hidden
• a no-match query filtered to 0 visible cards and made the no-results message visible
• confirmed generated dist/index.html includes role="status" and aria-live="polite" on the no-results message
• git diff --check origin/main...HEAD -> clean

Generated .astro/dist output was restored after validation.