Enterprise hardening, ORM/SWC fixes, Go 1.26.6, and CI lint green

[ATRIwOX]

Summary

Merges dev → main with production-hardening, ORM/workspace fixes, toolchain/CI updates, and a clean golangci-lint gate.

• Security / trust boundaries: harden password writes and production defaults; security headers, session CSRF, webhook dial pinning; schema context, setup-token gate, metrics trust; LICENSE update.
• ORM / workspace: unify falsy domain semantics (including Many2One false → NULL); batch RPC read and related-field enrichment; restore Many2One search/select-style autocomplete; sys.action.url / iframe URL actions.
• Ops / docs: sliding sessions, container deploy, HA/SSO runbooks; additive schema sync and DDL production policy.
• Toolchain / CI: Go 1.26.6 (stdlib vulns); bump x/crypto and gpdf; go vet + golangci-lint (Close excluded from errcheck); dedicated govulncheck job; Node 24 + golangci-lint-action@v9; make lint wired into local check.

Test plan

• CI green on this PR (go-build, go-test, go-lint, go-vuln, swc, generate)
• Local: make lint and go test ./test/... -count=1
• Smoke: login, Many2One search/create/select, URL action iframe, form CSRF/session still work
• Confirm production config defaults / secrets env overrides still match sumeru.conf.example and docs
• Optional: integration job / Postgres path if enabled for the release cut