[AI Improvement] [Task] Upgrade astro devDependency from ^2 to ^7 and fix Astro type usage

[joehan]

Resolves Buganizer b/567662586

Proposed Improvement

Upgraded the astro devDependency from ^2.2.3 to ^7.3.5 and regenerated npm-shrinkwrap.json using npm@11.9.

Key changes:

• In package.json, bumped astro to ^7.3.5.
• In src/frameworks/astro/utils.ts, replaced the typeof import("astro/dist/core/config/config") type annotation for legacy openConfig with an explicit local LegacyAstroConfigModule interface. Astro 7 no longer exports openConfig, but runtime user projects on older Astro versions (<2.9.7) still dynamically import it when detected. The local interface maintains complete backward compatibility for those user projects without causing TypeScript compilation errors against Astro 7.
• Normalized npm-shrinkwrap.json with npx -y npm@11.9 install --package-lock-only --ignore-scripts.
• Clears high and critical audit vulnerabilities pulled in by Astro 2 (astro, @astrojs/markdown-remark, devalue, deepmerge-ts, cookie, and the nested legacy undici copies in @astrojs/telemetry and @astrojs/webapi).

Verification

• npm run build: Passed cleanly.
• npm run lint:quiet: Passed with 0 errors.
• npm run test:compile: Passed with 0 errors.
• npx mocha 'src/frameworks/astro/**/*.spec.ts': All 9 tests passing.
• npm audit: Verified that vulnerabilities from astro, devalue, deepmerge-ts, @astrojs/*, and cookie are resolved.

[gemini-code-assist]

Code Review

This pull request upgrades the astro dependency to version 7.3.5 and refactors the configuration loading in src/frameworks/astro/utils.ts to use a local LegacyAstroConfigModule interface. Feedback on the changes points out a violation of the repository style guide regarding the use of any and unknown types, suggesting a more robust type definition for the Astro configuration and logging parameters.

[gemini-code-assist]

According to the repository style guide (GEMINI.md, line 37), we should never use any or unknown as an escape hatch. Instead, we should define proper interfaces/types.

We can define a proper LegacyAstroConfig interface representing the expected shape of the Astro configuration object, and type logging as undefined since it is not used here.

    interface LegacyAstroConfig {
      outDir: string | URL;
      publicDir: string | URL;
      output: string;
      adapter?: { name: string };
    }
    interface LegacyAstroConfigModule {
      openConfig: (options: {
        cmd: string;
        cwd: string;
        logging?: undefined;
      }) => Promise<{ astroConfig: LegacyAstroConfig }>;
    }
    const { openConfig }: LegacyAstroConfigModule = await dynamicImport(configPath);
    const logging = undefined;
    const { astroConfig } = await openConfig({ cmd: