fix: implement the session-close Tags:-line exclusion announced in v0.113.1

[bborbe]

What

Phase 8.6 check #2 in commands/session-close.md resolved every [[Target]] on a page as a page link, including wikilinks on the Tags: line. Vaults tag with wikilink syntax for tags that intentionally have no page, so the check reported the vault's own convention as breakage.

Check #2 now skips wikilinks on a line matching ^Tags: — body links only.

Why it matters

Observed 2026-08-20: [[OmniFocus]] was flagged on a generated recurring task. It turned out to be one of 14 unresolved tag names across that vault's 74 generated tasks ([[Backup]] ×7, [[Planning]] ×5, [[Review]] ×4, [[Finance]] ×4, …) — house style, not a broken link.

The cost was not just noise. The false flag sent the operator to "fix" the task's source template in another repo, where the proposed one-file change would have created drift against 73 sibling schedules. A check that manufactures work is worse than no check.

Note on v0.113.1

v0.113.1's changelog already describes this fix, but the code never shipped — that bullet was folded into a commit touching CHANGELOG.md and commands/sync-progress.md only, never commands/session-close.md. So the release announced a fix that was absent. This PR lands the rule itself. The v0.113.1 section is left as written rather than rewritten after release; the new ## Unreleased bullet records what happened.

Verification

Markdown-only, 2 lines added. Local make precommit was not used as a gate: this machine has golangci-lint v1.64.8 while the repo bumped to v2.12.2, so it fails on nine untouched pkg/ops/*.go files. Master's CI is green and the diff cannot affect Go lint. CI on this PR is the real check.

[ben-s-pull-request-reviewer]

{
"verdict": "approve",
"summary": "The PR correctly implements the Tags:-line wikilink exclusion in `session-close` Phase 8.6 check #2. The `^Tags:` pattern is precise, the exclusion is correctly scoped to wikilinks on that line only, and the diff is minimal and clean — exactly 2 files, 6 lines added, no unintended side effects. The new paragraph is well-grounded with the real-world observed case (OmniFocus tag across 14 generated tasks).",
"comments": [],
"concerns_addressed": [
"correctness: The `^Tags:` pattern correctly identifies the Tags line — anchored at line start, matches the literal `Tags:` prefix used by vault convention. The exclusion applies only to wikilinks on that line, not to other link types or other lines.",
"correctness: Diff shows exactly the intended change — CHANGELOG.md (+4 lines for the Unreleased entry) and commands/session-close.md (+2 lines for the exclusion rule paragraph). No side effects, no unrelated changes."
]
}