audit 6: documents, comments, dead code and staticcheck; the test gaps closed

The last stage of the 2026-10-12 audit; no cut.

Doc drift: architecture.md (the sender check in § OpenDKIM, the limit:
row's 48 hours, the inbound log and filter-list routes and who may open
them, migrations to 0011 and every table, KitPage as production data,
Reload configuration as a restore writes, the panel's roles counted),
schema-migrations.md (tables and columns since v2), guide.md (a delivery's
lines go at the next prune; INBOUND_JOURNAL_MILTER_SOCKET moved to
architecture.md's internal list), development.md (the env guard, the
deferral the e2e proves, its fixed sleeps), roadmap.md.

Comments say what the code does now; TestBaselineIsTheOnlyMigration is
TestChainStartsAtTheBaseline; the milter package doc names its three
milters.

Dead code gone: view.Facts, dmarc HostedSuggestion and
ValidateHostedAddress, app UpdateMode (each with the test that alone kept
it), the method checks the method-bound routes made dead;
Settings.WithResult calls resultFlash. staticcheck 2026.1 in test.yml on
both modules, clean: the e2e package builds without its tests now (a test
and two constants moved out of non-test files), three findings fixed.
The test moved, TestImageBuildPreservesLogrotateMode, had sat in a
non-test file and never run; run, it failed on the entrypoint (docker run
without a hostname) and now asks with --entrypoint stat.

The test gaps no step named, each closed: follow() with mail.log gone past
blindMin and made again; CheckRestore with a manifest that is not JSON;
the origin check with a port; every /server/ pattern in web.go through
server() and in the routes table (it found GET /server/health/fragment
missing from the table - guarded, not tested); L9 as the owner decided it
on 2026-10-12, the comment on senderSession.Headers and the test passing
an h that holds the earlier messages' From:.

Plan stage 6 ticked; roadmap audit row done, 81/81.

Tested on the test server: go vet + go test of 27 packages, make e2e (all
pass, 513 s) on this tree; staticcheck locally on both modules.

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

docs/roadmap.md

@@ -46,7 +46,7 @@ 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 | in progress (stage 0 shipped `2.4.2`, stages 1+2 `2.5.0`, 2b `2.5.1`, 2c `2.5.2`, 3 `2.5.3`, 4 `2.5.4`, 5 `2.6.0`; next stage 6, docs only) | 77/81 | [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 | done 2026-10-15 (stage 0 shipped `2.4.2`, stages 1+2 `2.5.0`, 2b `2.5.1`, 2c `2.5.2`, 3 `2.5.3`, 4 `2.5.4`, 5 `2.6.0`; stage 6 docs and tests, no cut) | 81/81 | [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
@@ -57,9 +57,9 @@ shipped as `2.2.0` the same day, **panel-notifications** as `2.3.0` and
 [audit-2026-10-12](audit-2026-10-12.md) shipped as `2.4.2` (2026-10-14), its
 stages 1 and 2 as `2.5.0` the same day, stage 2b as `2.5.1`, stage 2c as
 `2.5.2` (2026-10-15), and stages 3, 4 and 5 as `2.5.3`, `2.5.4` and
-`2.6.0` the same day.
-Nothing is agreed after it: every remaining
-item is a candidate. panel-docs shipped in
+`2.6.0` the same day; stage 6 (documents and tests, no cut) closed the
+audit. What is agreed after it is marked so in the index; every other
+remaining item is a candidate. panel-docs shipped in
 [CHANGELOG.md](../CHANGELOG.md) `[1.8.0]`; dmarc-reports in `[1.7.0]`
 (its ingest path first ran in `2.0.0` and was reviewed on 2026-10-11, see
 [security.md](security.md)); domain-stats-auto-ratelimit in
@@ -67,17 +67,16 @@ item is a candidate. panel-docs shipped in
 queue-retries in `[1.3.1]`; the 2026-08-13 full-tree review follow-ups are in
 `[1.3.0]`. Candidates need explicit agreement before they join the queue.
 
-The 2026-08-19 full-tree code review is closed except for four items, all
-listed above and none of them urgent: [origin-strict](#origin-strict) (its
-"add CSRF tokens", decided otherwise on 2026-10-13),
-template-data-typing (done by `2.0.0`; its last map is a step of
-[audit-2026-10-12](audit-2026-10-12.md) stage 4),
-structured-logging ([dropped](#dropped-with-the-condition-for-return) on
-2026-10-13) and
-[review-2026-08-followups](#review-2026-08-followups). What that review
-produced is in [CHANGELOG.md](../CHANGELOG.md) `[1.9.2]`; its own document
-was removed once these four items carried everything still open, and stays in
-git history.
+The 2026-08-19 full-tree code review is closed except for one item, listed
+above and not urgent: [origin-strict](#origin-strict) (its "add CSRF tokens",
+decided otherwise on 2026-10-13). Of its other three,
+template-data-typing is done (the last untyped map, the health sampler's, went
+in [audit-2026-10-12](audit-2026-10-12.md) stage 4, `2.5.4`),
+structured-logging is [dropped](#dropped-with-the-condition-for-return)
+(2026-10-13) and [review-2026-08-followups](#review-2026-08-followups) is
+closed (2026-10-14). What that review produced is in
+[CHANGELOG.md](../CHANGELOG.md) `[1.9.2]`; its own document was removed once
+these four items carried everything still open, and stays in git history.
 
 After a context reset, pick an item marked `agreed` or `in progress`, then work
 the **Implementation checklist** in its linked plan. The `Progress` column above