feat(ci): compile only shard-assigned packages in unit test shards

[quirogas]

Right now, every unit test shard runs pnpm run compile (turbo run compile --filter='...[HEAD^1]') before starting ci/run_conditional_tests.sh. On large PRs, that means all 15 shards compile every changed package in the repo, even though each shard only tests a fraction of them. On the flip side, if a PR only touches ci/, run_conditional_tests.sh runs tests for all packages, but --filter='...[HEAD^1]' sees no changed packages and compiles nothing.

This PR moves the turbo run compile step into ci/run_conditional_tests.sh after the shard's package list is calculated, so each shard only compiles the packages it is actually going to test.

What changed

• ci/run_conditional_tests.sh: Calculate shard_dirs first and run turbo run compile filtered only to the directories assigned to that shard (--filter={./<dir>}). Also replace ls -d in the directory loop with standard bash globbing.
• .github/actions/run-unit-tests/action.yaml & .github/workflows/presubmit-bun.yml: Remove the top-level pnpm run compile step (since run_conditional_tests.sh now handles it) and include the shard index in the .turbo cache key.
• .github/workflows/presubmit.yaml: Skip pnpm run compile in the lint job when no .ts files changed in the PR.
• .github/actions/check-shard-status/action.yaml: Add per_page: 100 when listing workflow jobs so runs with more than 30 jobs don't miss shard results.

[gemini-code-assist]

Code Review

This pull request optimizes the CI workflow by introducing shard-specific Turborepo caching and compiling only the packages assigned to each shard within ci/run_conditional_tests.sh. It also increases the page size for fetching workflow jobs and refines OS and path matching for Windows environments. Feedback highlights two key improvements: first, correcting the Turborepo filter syntax from ./${d%/}... to ..../${d%/} to ensure that local monorepo dependencies are compiled first; second, replacing the use of ls in a bash loop with direct shell globbing to make the script more robust and idiomatic.