feat(frameworks): add Astro framework detection

[0x4bs3nt]

Summary

• Add detection support for the Astro meta framework.
• Includes signature detection, version extraction and tests with full signature coverage.

Features

• Seven signatures to match against for Astro detection
• Tests covering all seven signatures
• Version extraction

Test plan

• gofmt applied
• framework unit tests passing (go test ./internal/scan/frameworks)
• go vet passes
• manually tested on Astro websites

[vmfunc]

nice work on the astro detection! tested locally and everything passes - unit tests, go vet, gofmt all good.

one small thing - the generator meta weight is 0.6 but all other meta-framework detectors use 0.5 as max:

• next.js: __NEXT_DATA__ → 0.5
• nuxt: __NUXT__ → 0.5
• sveltekit: __sveltekit → 0.5
• gatsby: ___gatsby → 0.5
• remix: __remixContext → 0.5

left a suggestion on that line to match the convention. otherwise lgtm 👍

[0x4bs3nt]

nice work on the astro detection! tested locally and everything passes - unit tests, go vet, gofmt all good.

one small thing - the generator meta weight is 0.6 but all other meta-framework detectors use 0.5 as max:

* next.js: `__NEXT_DATA__` → 0.5

* nuxt: `__NUXT__` → 0.5

* sveltekit: `__sveltekit` → 0.5

* gatsby: `___gatsby` → 0.5

* remix: `__remixContext` → 0.5

left a suggestion on that line to match the convention. otherwise lgtm 👍

Oops, sorry, missed that. Should be all good now.