fix: eliminate cache-memory dependency in update-instructions workflow (#8739)

* fix: eliminate cache-memory dependency in update-instructions workflow

Replace the cache-memory tool (used to store last-run.txt) with a GitHub
API query for the last successful workflow run. This fixes the false-positive
cache-miss failure on first run, where the agent correctly reported
missing_data/cache_memory_miss but gh-aw's detection layer interpreted it
as a prompt misconfiguration.

The workflow run history is the natural, always-available source of truth
for "when did this last succeed" — no external state to seed, evict, or
misread. This also avoids the 7-day cache eviction risk that could cause
repeated first-run behavior on a weekly schedule.

Fixes #8702

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

* fix: add actions toolset so agent can list workflow runs

The github MCP toolsets only had [pull_requests, issues, repos] but Step 1
requires listing workflow runs to find the last successful run date. Without
the actions toolset, the agent would always fall through to the 6-month scan.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

* chore: regenerate lock file with gh-aw v0.81.6

Recompile the lock file to reflect the cache-memory removal and actions
toolset addition. Also upgrades gh-aw infrastructure from v0.79.8 to
v0.81.6 with updated container images and SHA-pinned digests.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

---------

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Author: vhvb1989

.github/aw/actions-lock.json

@@ -25,15 +25,10 @@
       "version": "v7.0.1",
       "sha": "043fb46d1a93c77aae656e7c1c64a875d1fc6a0a"
     },
-    "github/gh-aw-actions/setup-cli@v0.79.8": {
-      "repo": "github/gh-aw-actions/setup-cli",
-      "version": "v0.79.8",
-      "sha": "c0338fef4749d08c21f8f975fb0e37efa17dda47"
-    },
-    "github/gh-aw-actions/setup@v0.79.8": {
+    "github/gh-aw-actions/setup@v0.81.6": {
       "repo": "github/gh-aw-actions/setup",
-      "version": "v0.79.8",
-      "sha": "c0338fef4749d08c21f8f975fb0e37efa17dda47"
+      "version": "v0.81.6",
+      "sha": "ba6380cc6e5be5d21677bebe04d52fb48e3abec7"
     }
   }
 }