Docs cleanup: fix Client constructor examples and document new SDK features

[jpetey75]

Tracking issue for a docs pass (to be bundled with the upcoming bulk docs update). Kept separate from the feature PRs to keep those small.

Bugs to fix

• docs/SDK_GUIDE.md uses the wrong Client(...) signature. Lines 10 and ~383 show Client(base_url=..., token=...), but the real constructor is Client(instance_url=..., access_token=..., project_uuid=...) (the README is correct). Copy-pasting the guide snippet currently fails.

Features to document (landing via open/merged PRs)

• Multiple filters on the same dimension field — e.g. date ranges (dim >= a) & (dim <= b) (Support multiple filters on the same dimension field #20, merged in feat: support multiple filters on the same dimension field #22). (SDK_GUIDE already updated in that PR — verify it reads well.)
• Filtering on table calculations — TableCalculation + .table_calculations(...) + filtering on calc values (Support filtering on table calculations #21, PR feat: support filtering on table calculations #24).
• Fetching results beyond 50k — limits are now validated against the instance's query.maxLimit instead of a fixed cap; large fetches page at maxPageSize (Support fetching results beyond the 50k row limit #19, PR feat: fetch results beyond the old 50k row cap #25). Note the CSV-export path for >maxLimit extracts is still tracked in Support fetching results beyond the 50k row limit #19.
• Service account tokens — ldsvc_ tokens now authenticate via Bearer automatically (Support service account tokens #17, PR Set auth header to Bearer to support service accounts #18). A short README note was added in that PR; consider mirroring it in the SDK guide / any auth section.

Nice-to-have

• Align the SDK_GUIDE.md Quick Start with the README (same constructor, same auth guidance).

[linear-code]

PROD-8538