feat: filter project selector by typed prefix

[almogdepaz]

summary

• filter the fetched project list locally by case-insensitive name prefix
• restore the full list for blank input without refetching
• autofocus the project-name input and clarify its placeholder
• preserve existing project selection and typed-project creation flows

verification

• GIT_CONFIG_COUNT=1 GIT_CONFIG_KEY_0=commit.gpgsign GIT_CONFIG_VALUE_0=false bun test — 1,831 passed
• bunx playwright test — 108 passed, 126 expected skips
• bun run typecheck
• git diff --check
• live desktop click path confirmed focus and placeholder after server-only deployment

closes #178