v1.17.0.0: rebump again — bump-detection now classifies branch as MINOR

CI's version-stale check (job 73106360896) failed: PR #1234 claims v1.16.1.0
but the queue moved to v1.17.0.0. Root cause: bumping 1.15.1.0 → 1.16.1.0
to dodge the prior collision turned the branch's diff classification from
PATCH (1.15.0 → 1.15.1) into MINOR (1.15.0 → 1.16.x). detect-bump.ts now
sees MINOR, gstack-next-version walks the MINOR lane past #1233's
v1.16.0.0 claim, and the next free slot is v1.17.0.0.

Honestly accurate per CLAUDE.md scale-aware bumps: this branch IS a
MINOR ("substantial new capability shipped — skill, harness, command,
big refactor"). The new helper + migration + integration totals ~1200
lines added across 11 files with 26 new tests. PATCH was always the
wrong honest classification; the queue collision forced the right
answer.

Files updated:
- VERSION                                                     1.16.1.0 → 1.17.0.0
- package.json                                                1.16.1.0 → 1.17.0.0
- CHANGELOG.md heading + After column                         1.16.1.0 → 1.17.0.0
- CHANGELOG removal targets                                   1.17.0.0 → 1.18.0.0
- gstack-upgrade/migrations/v1.16.1.0.sh                      → renamed v1.17.0.0.sh + log prefix
- bin/gstack-brain-consumer "DEPRECATED in" + "removal in"    1.16.1.0/1.17.0.0 → 1.17.0.0/1.18.0.0
- bin/gstack-brain-uninstall "since vX.Y.Z.W"                 1.16.1.0 → 1.17.0.0
- test/gstack-upgrade-migration-v1_16_1_0.test.ts             → renamed v1_17_0_0.test.ts

26/26 tests still pass. No behavior change.

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

package.json

@@ -1,6 +1,6 @@
 {
   "name": "gstack",
-  "version": "1.16.1.0",
+  "version": "1.17.0.0",
   "description": "Garry's Stack — Claude Code skills + fast headless browser. One repo, one install, entire AI engineering workflow.",
   "license": "MIT",
   "type": "module",