ci: lint the example module

[tthayer]

What

Adds example/ to the go-lint CI job and fixes the 27 findings that were hiding there.

example/ is a separate Go module, so the root golangci-lint invocation never reached it — despite it carrying every integration test in the repo, including the only coverage of the partitioned-parent ALTER suppression (SQLSTATE 42809) added in #159/#160.

Findings fixed (27 → 0)

Fix	Count
--fix (whitespace, godot)	9
revive var-naming: fakeTenantIds→fakeTenantIDs, masterSelectSql→masterSelectSQL, fmtSql→fmtSQL, selectSql→selectSQL, eventIds→eventIDs	14
forbidigo: dropped a leftover debug fmt.Println()	1
gosec G115: strconv.ParseInt(s, 2, 64) → ParseUint(s, 2, 8) in bitStringToBytes, so the byte() conversion is structurally bounded rather than merely bounded in practice	1
revive line-length-limit: hoisted a 201-char query into const updatedPetQuery	1

The one config carve-out

gomoddirectives flags example/go.mod's replace github.com/ductone/protoc-gen-pgdb => ../, which is how the example module consumes the in-repo library and must stay.

Note this is not expressible via the existing replace-allow-list setting — that governs non-local replacements only, and the firing check here is the separate replace-local boolean. Rather than flip replace-local: true (which would disable the check for the root go.mod too), the exclusion is scoped to the single file.

Verified scoped, not blanket: with a local replace temporarily added to the root go.mod, gomoddirectives still fires on it.

Verification

• golangci-lint run clean in both modules
• go test ./... passes in both modules (example/ integration tests against PG16 + pgvector)

Closes IGA-3723.

🤖 Generated with Claude Code

[linear-code]

IGA-3723

[tthayer]

Closing unmerged: linting example/ is test-only hygiene and not worth a permanent CI check. Branch retained if this is ever revisited.