deps: modernc.org/sqlite 1.60.1, x/crypto 0.58.0, x/sys 0.49.0 (audit stage 0)

- go get ...@latest + go mod tidy: sqlite 1.53.0 -> 1.60.1 (libc
  1.77.1, memory 1.12.1), x/crypto 0.54.0 -> 0.58.0, x/sys 0.47.0 ->
  0.49.0, go-isatty 0.0.24. The go line reads 1.26.0 (tidy's spelling of
  1.26); no dependency asks for a newer Go.
- development.md: golang:1.26-bookworm floats to the newest patch, and
  the standard library's security fixes arrive that way - rebuild the image
  after each Go patch release; dependencies are raised by hand.
- CHANGELOG [Unreleased], audit plan line ticked, roadmap 5/61.

Evidence on the test server (Go 1.26.5) for this tree plus the next
commit's staticcheck fixes: go vet clean, go test ./... 23 packages ok,
make e2e exit 0.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

docs/roadmap.md

@@ -42,7 +42,7 @@ in `git log` and [CHANGELOG.md](../CHANGELOG.md).
 | from-header-binding | Hold a message's `From:` header against the application that sends it | shipped `2.4.0` | 9/9 | [plans/from-header-binding.md](plans/from-header-binding.md) |
 | panel-redesign | Panel redesign (accepted mockups, design contract) | shipped `2.0.0` | 27/27 | [plans/panel-redesign.md](plans/panel-redesign.md) |
 | schema-squash | Squash SQLite migrations into a 2.x baseline | built in panel-redesign (stage 1) | — | [plans/panel-redesign.md](plans/panel-redesign.md) |
-| audit-2026-10-12 | Follow-ups of the 2026-10-12 full-tree code audit, seven stages | agreed (2026-10-12: stage 0 first, then 1+2; the rest after) | 4/61 | [audit-2026-10-12.md](audit-2026-10-12.md) |
+| audit-2026-10-12 | Follow-ups of the 2026-10-12 full-tree code audit, seven stages | agreed (2026-10-12: stage 0 first, then 1+2; the rest after) | 5/61 | [audit-2026-10-12.md](audit-2026-10-12.md) |
 
 **Recommended order** (not binding; owner, 2026-10-09: feature order follows
 development convenience): **panel-redesign** shipped as `2.0.0` (2026-10-11) and