Update go toolchain directive to v1.25.12 (release-v0.8)

[renovate]

This PR contains the following updates:

Package	Type	Update	Change
go (source)	toolchain	patch	1.25.7 → 1.25.12

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Release Notes

golang/go (go)

v1.25.12

v1.25.11

v1.25.10

v1.25.9

v1.25.8

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[fullsend-ai-review]

🤖 Finished Review · ✅ Success · Started 10:04 PM UTC · Completed 10:10 PM UTC
Commit: 7c8ccca · View workflow run →

[fullsend-ai-review]

Review — Approve ✅

Mechanical Renovate bot PR bumping the Go toolchain directive from go1.25.7 → go1.25.12 across both the acceptance/ and docs/ modules. The go.mod dependency cleanup removes ~25 stale indirect packages that are no longer needed by the transitive dependency graph (confirmed by go mod tidy under the updated toolchain). The go.sum changes are consistent checksum regeneration.

Dimensions reviewed

Dimension	Result
Correctness	✅ No issues. Removed indirect deps are not directly imported — the acceptance module imports only godog and conforma/cli. go/toolchain directive compatibility verified. No stale references to removed packages or old toolchain version remain in the repo.
Security	✅ No issues. No secrets, no malicious replace directives, no suspicious dependency additions. Removing stale indirect deps reduces attack surface.
Intent & coherence	✅ Mechanical change — authorization implicit from Renovate bot automated maintenance.
Style & conventions	✅ No findings — mechanical/generated change follows existing patterns.
Documentation currency	✅ No findings — no public API, CLI, or behavioral changes requiring doc updates.
Cross-repo contracts	⏭ Skipped — no exported interfaces, schemas, or public APIs modified.