fix: global types support for jsr.io

[CodeMaverick-143]

Fixes JSR global types support (addresses TODO in src/globals.ts).

Previously, proper type definitions for globals like $, fs, and path were missing when importing from JSR, causing type errors in consumer projects and failures during jsr publish. I've added the missing declare global block to src/globals-jsr.ts, adjusted tsconfig.json to avoid duplicate identifier conflicts during the build, and updated the JSR integration tests to allow global augmentations (which are necessary but flagged as "slow types" by JSR).

// Now works correctly in JSR-compatible environments (e.g. Deno)
import 'jsr:@webpod/zx/globals'

await $`echo "Global types are now working!"`

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