docs: sweep minor documentation and comment drift (audit #16)

[sbalabanov]

Summary

Documentation and comments had drifted from the actual code in several places, causing confusion for readers who trust the docs as ground truth.

Changes

• docs/errors/errors.md: fix the ErrorCode.String() default description; add the missing Fields export to the API index; rename ErrDownloadBazeliskNetwork to ErrNetwork; align the classifyBazelClientError fallthrough with NewInfra; and fix the proto string spelling.
• controller/README.md: remove false claims about a Config collaborator and per-repository config provider.
• README.md: remove the stale "and services" wording and replace nonexistent generated interfaces in the mockgen example.
• example/cmd/query-bench/main.go: fix the Bazel label to //example/cmd/query-bench.
• Makefile: add version to .PHONY.

The metrics naming comment originally included in this PR is no longer part of the diff because latest main already contains a more precise version of that correction.

Test Plan

• make gazelle (no generated changes)
• ./tools/bazel test //... --test_output=errors --test_env=GIT_CONFIG_COUNT=1 --test_env=GIT_CONFIG_KEY_0=commit.gpgSign --test_env=GIT_CONFIG_VALUE_0=false

Revert Plan

Revert commit 890913e0d52b7c2ccd2afc0c5ff754abfbda2306.

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