Replace skill-failure noop with manual-analysis fallback (#134)

Reverses the strict abort rule from #133 in the openings, applies-to,
and style sweeps. Real-run evidence (elastic/docs-content runs
25377518194 + 25378183549, both openings) showed the hardened
"two failures = noop" rule firing prematurely:

- 13:09:34  ✗ skill(docs-page-opening-optimizer) Skill not found
- 13:09:37  ✗ skill(docs-page-opening-optimizer) Skill not found
- 13:09:41  ● noop "skill unavailable — confirmed after exact-form attempts"
- 13:14:36  ● create_issue "shard 20/28 — 20 pages"   ← agent eventually produced
                                                        an issue, but suppressed
                                                        because noop already fired

The agent's tool serialization keeps logging the skill call as
`skill(docs-X)` — without the `skill:` prefix — which always
returns "Skill not found" from Copilot CLI. Whether the agent's
underlying invocation was actually reformatted, or whether it's a
log-rendering quirk, doesn't matter: my hardening committed the
agent to noop after two of these "failures", before it had a chance
to do useful work.

Replace with frontmatter's softer pattern: try the skill once; if
"Skill not found" comes back, fall back to manual analysis using
bash + the agent's own judgment, and note the skill failure once
in the issue body's Notes section. Only noop if even manual
analysis produces no high-confidence findings.

Applied uniformly to:
- gh-aw-docs-openings-sweep.md (the sweep that's been noop'ing)
- gh-aw-docs-applies-to-sweep.md
- gh-aw-docs-style-sweep.md

Frontmatter, coherence, staleness, typos already had softer or
deterministic-only fallback paths and don't need this change.

Co-authored-by: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: theletterf

.github/workflows/gh-aw-docs-applies-to-sweep.lock.yml

@@ -205,13 +205,12 @@ Invoke `skill(skill: docs-applies-to-tagging)` against `/tmp/gh-aw/sweep-data/sc
 
 **Audit mode only — do not write any files.** The skill defaults to validation when not asked to fix; reinforce that intent in the call. This sweep produces an issue, not edits.
 
-**Only treat the skill as unavailable after a confirmed exact-form failure.** Stochastic agent retries sometimes invoke the skill with a shortened form (e.g., `skill(docs-applies-to-tagging)` without the `skill:` prefix) which fails before the exact form is tried. Procedure:
+**If the skill returns "Skill not found", do not noop.** That error is ambiguous — it can mean the skill genuinely isn't installed, or that the invocation form was reformatted by the agent's tool serialization. Either way: fall back to manual analysis instead of aborting. Procedure:
 
-1. Invoke with the exact form `skill(skill: docs-applies-to-tagging)`.
-2. If the result is "Skill not found", retry once more with the same exact form.
-3. Only after a second exact-form failure, abort the run by calling `noop` with `"docs-applies-to-tagging skill unavailable"` — there is no fallback heuristic worth filing as findings.
+1. Try invoking the skill with the exact form `skill(skill: docs-applies-to-tagging)`.
+2. If that fails or returns "Skill not found": fall back to **manual analysis**. Use `bash` to scan each in-scope file's frontmatter (the YAML block at the top), checking for missing/invalid `applies_to` keys against the documented allowed values. Produce findings as you would have from the skill output, and add a single line in the issue body's `Notes` section: "skill `docs-applies-to-tagging` did not produce output in this run; findings are agent-only."
 
-A single first-attempt failure (especially with a non-exact form) is **not** sufficient evidence to noop.
+Only call `noop` if you cannot produce any high-confidence findings even from manual analysis.
 
 ## Step 2: Build the findings list