Bring main's fixes into next (closes #16)

Merges main into next as a two-parent merge, so main becomes an ancestor
of next and the later merge of next into main does not conflict. This
brings in golangci-lint v2.12.2 with .golangci.yml, and the fix that
makes every handler emit slog attributes.

README.md and TODO.md conflicted. README.md keeps main's Attribute
output section, followed by next's Entrypoints section. TODO.md keeps
the completed steps from both sides, newest first. The other files
merged cleanly: the Makefile is still next's script/ shims, and the
Dockerfile has main's v2.12.2 lint image.

Model: opus-5-5

TODO.md

@@ -24,6 +24,15 @@ files it depends on: .golangci.yml, REPO_POLICIES.md, .editorconfig,
 
 # Completed Steps
 
+* 2026-08-10: fixed every handler discarding slog attributes: console,
+    JSON and webhook handlers now emit record attributes, accumulate
+    WithAttrs without mutating the receiver, and honour WithGroup;
+    slog.Group values nest and LogValuer values are resolved; console
+    keys and values holding invalid UTF-8 are quoted
+* 2026-08-07: added canonical `.golangci.yml` (v2 schema), pinned the
+    `Dockerfile` lint stage to golangci-lint v2.12.2 (tag+digest), and
+    fixed all findings the v1→v2 jump surfaced without changing any
+    exported signatures or behavior
 - 2026-07-07 Adopted scripts-to-rule-them-all: `script/` entrypoints,
     Makefile shims, README Entrypoints section
 * 2026-02-08: fixed JSONHandler deadlock from recursive log.Println,
@@ -48,6 +57,8 @@ files it depends on: .golangci.yml, REPO_POLICIES.md, .editorconfig,
     the working tree
 * Pick one tag scheme before the next release (v1.0.0 vs 1.0.1 are
     inconsistent)
+* Tag v1.0.2, with the leading v, once the attribute fix lands, so
+    consuming repos can move off pseudo-version pins in one step
 * Fix RELP output to cache (from old TODO)
 * Re-add RELP delivery over TCP to remote rsyslog imrelp; removed
     2024-06-14 because it did not build (README planned feature)