fix: add guidance when search-attribute create hits per-type limit

[amit-writes-code]

Related issues

Closes #318 (partial)

This PR addresses 1 of the 3 approaches discussed for issue #318:

1. ⬜ Raise the defaults for the dev server — not done (server-side schema concern, see note below)
2. ⬜ Expose a CLI flag like --custom-search-attributes-limit — not done
3. ✅ Improve the error message when hitting the limit — done in this PR

What changed?

temporal operator search-attribute create previously surfaced the server's
per-type limit failure as a bare unable to add search attributes: ... cannot have more than 3 search attribute of type Text., which gives the user no idea
why the limit exists or what to do next.

With SQL-based Visibility, custom search attributes are mapped onto a fixed pool
of pre-allocated fields per type, so this limit cannot be raised at runtime. When
this specific error is detected, the command now appends a short hint: remove an
unused attribute of that type, reuse an existing one, choose a different type, or
use Elasticsearch-based Visibility (which has no per-type limit), plus a docs
link. All other failures are forwarded unchanged.

Scope note: issue #318 also suggests raising the default max (approaches 1 and 2
above). The per-type pool size is fixed in the visibility schema, not a runtime
setting, so raising it is a server-side schema concern rather than something the
CLI can pass through. This PR therefore intentionally addresses only the
error-message portion (approach 3); the other two can be tackled separately.

Checklist

Stability

• Breaking changes are marked with 💥 in the PR title and release notes — n/a, not breaking
• Changes to JSON output (-o json / -o jsonl) are treated as breaking changes — n/a, no JSON structure change

Design

• This feature does not depend on Cloud-only APIs or behavior (it works against an OSS server)

(Remaining Design items removed — no new commands or flags.)

Help text

(Removed — no changes to commands.yaml or help text; the change is in the command's run error path.)

Behavior

• Results go to stdout; errors and warnings go to stderr
• Error messages are lowercase with no trailing punctuation — the CLI-added clause is lowercase and ends on the docs URL; the leading capital/period belong to the wrapped upstream server error (unchanged)

Tests

• Added functional test(s) (SharedServerSuite) — TestOperator_SearchAttribute_LimitGuidance
• Added unit test(s) (func TestXxx) where applicable — covered by the functional test

Manual tests

Setup

temporal server start-dev --headless

Happy path

$ temporal operator search-attribute create \
    --name MyText1 \
    --type Text
Search attributes have been added

Error case

$ for i in 1 2 3 4; do
    ./temporal operator search-attribute create --name "MyText$i" --type Text
  done
Search attributes have been added
Search attributes have been added
Search attributes have been added
Error: unable to add search attributes: Unable to create search attributes: cannot have more than 3 search attribute of type Text.; this per-type limit is fixed for sql-based visibility and cannot be raised at runtime, so remove an unused attribute of this type, reuse one, choose a different type, or use elasticsearch visibility which has no per-type limit: https://docs.temporal.io/visibility
$ echo $?
1

Composition

$ temporal operator search-attribute create --name MyText1 --type Text
$ temporal operator search-attribute list

[CLAassistant]

All committers have signed the CLA.

[amit-writes-code]

@chaptersix seems the build is taking forever to run, I squashed 2 commits into 1 could that be the reason?