feat(#1866): agent-side self-load of configured agent_skills

Each of the 22 consumer agents now self-loads its configured agent_skills
in its mandatory init step, so .planning/config.json agent_skills.<type>
reaches the agent on every runtime — including Cursor and /gsd-autonomous,
where Skill()-delegated workflow bash init did not reliably execute.

- gsd-core/references/agent-skills-bootstrap.md: shared contract
  (query + Read + dedup guard that skips when <agent_skills> is already
  in the prompt, so Claude's orchestrator-side injection never doubles)
- 22 agents/gsd-*.md: one self-load line naming the agent's own type
- gsd-core/workflows/autonomous.md: note that delegated agents self-load
- tests/agent-skills-bootstrap.test.cjs: regression + parity (CONSUMER_AGENTS
  bijection + fast-check property) — Generative-Fix-Divergence guard
- docs: ADR-1866, CONFIGURATION dual-injection How It Works, INVENTORY
  row, Changed changeset

Closes #1866

tests/fixtures/golden-install-parity/opencode.json

@@ -1,40 +1,40 @@
 {
   ".gsd-profile": "0e716a5fef4e6dc1",
   ".gsd/defaults.json": "560664b045e645cb",
-  "agents/gsd-advisor-researcher.md": "fc4eba63daf0b1ee",
+  "agents/gsd-advisor-researcher.md": "6955bcd8ca353de0",
   "agents/gsd-ai-researcher.md": "28a05307dad84020",
-  "agents/gsd-assumptions-analyzer.md": "cc0dbbd41e0a77a5",
-  "agents/gsd-code-fixer.md": "aa353a2a42b27981",
-  "agents/gsd-code-reviewer.md": "70deeb7ac7caf384",
-  "agents/gsd-codebase-mapper.md": "b9fd529aca682ccb",
+  "agents/gsd-assumptions-analyzer.md": "45c01017e84ba193",
+  "agents/gsd-code-fixer.md": "eb9fa698f827f23f",
+  "agents/gsd-code-reviewer.md": "2249774416314c57",
+  "agents/gsd-codebase-mapper.md": "948612acd505e87f",
   "agents/gsd-debug-session-manager.md": "09c805b7283633fd",
-  "agents/gsd-debugger.md": "610a3ff965f9fb6a",
+  "agents/gsd-debugger.md": "535cc597dcc0cade",
   "agents/gsd-doc-classifier.md": "cd4169adec56c26f",
   "agents/gsd-doc-synthesizer.md": "47a8b52fe974a810",
   "agents/gsd-doc-verifier.md": "65bbc2ae6b9ace29",
-  "agents/gsd-doc-writer.md": "b7acb2d8238c44c4",
+  "agents/gsd-doc-writer.md": "0696a8cdc0028917",
   "agents/gsd-domain-researcher.md": "71250e759ca9e723",
-  "agents/gsd-eval-auditor.md": "8975c9f3bca95bd5",
+  "agents/gsd-eval-auditor.md": "d9c7034244882d86",
   "agents/gsd-eval-planner.md": "60bddb70a937f796",
-  "agents/gsd-executor.md": "bcdc3f8bc334190a",
+  "agents/gsd-executor.md": "e185b21a5df49e0d",
   "agents/gsd-framework-selector.md": "1c0a10355e787675",
-  "agents/gsd-integration-checker.md": "69cfb2bbdfa56e28",
+  "agents/gsd-integration-checker.md": "a9de5928e5a5c649",
   "agents/gsd-intel-updater.md": "f9ef2797738b7f09",
   "agents/gsd-mempalace-curator.md": "aa7cf2c611057735",
-  "agents/gsd-nyquist-auditor.md": "b9b9e935503e63a5",
+  "agents/gsd-nyquist-auditor.md": "7a7e0d1cbafd6b63",
   "agents/gsd-pattern-mapper.md": "7c6d1d9817a9c1e7",
-  "agents/gsd-phase-researcher.md": "c206f5e7333fb2c9",
-  "agents/gsd-plan-checker.md": "f2c99e85291ce71b",
-  "agents/gsd-planner.md": "7a49c1bee3578da4",
-  "agents/gsd-project-researcher.md": "c70f9cf0d5593f09",
-  "agents/gsd-research-synthesizer.md": "a534bc0eaf1ac03b",
-  "agents/gsd-roadmapper.md": "6b8bdf6015939351",
-  "agents/gsd-security-auditor.md": "404f38e52ba883ff",
-  "agents/gsd-ui-auditor.md": "b040c900e8de2368",
-  "agents/gsd-ui-checker.md": "b98b00e586610657",
-  "agents/gsd-ui-researcher.md": "7ff5c528bef6af09",
+  "agents/gsd-phase-researcher.md": "6461af91c55b5227",
+  "agents/gsd-plan-checker.md": "5e9ec0d98f9a0059",
+  "agents/gsd-planner.md": "b4bc4916aadd24e0",
+  "agents/gsd-project-researcher.md": "f1d486fc0a3ff905",
+  "agents/gsd-research-synthesizer.md": "e0c2d9957431a1e1",
+  "agents/gsd-roadmapper.md": "1658a40b20d8b575",
+  "agents/gsd-security-auditor.md": "e36e436c0d5c26d5",
+  "agents/gsd-ui-auditor.md": "e810012e685b2466",
+  "agents/gsd-ui-checker.md": "5fd0ed65262dc194",
+  "agents/gsd-ui-researcher.md": "18dd700b1ac6d86a",
   "agents/gsd-user-profiler.md": "d825b4c0a6431f8b",
-  "agents/gsd-verifier.md": "47816fa1ba8a9b8b",
+  "agents/gsd-verifier.md": "e245bfb493a5c069",
   "command/gsd-add-tests.md": "b9cd93ed01945f75",
   "command/gsd-ai-integration-phase.md": "9d4bc4dcce7f1ee0",
   "command/gsd-audit-fix.md": "5615403843d5e491",
@@ -117,6 +117,7 @@
   "gsd-core/contexts/research.md": "b3285d8e7209cc3b",
   "gsd-core/contexts/review.md": "dc578fdd74bbea11",
   "gsd-core/references/agent-contracts.md": "ff65e633c656c0d2",
+  "gsd-core/references/agent-skills-bootstrap.md": "51b5d0ba5b1e98d9",
   "gsd-core/references/ai-evals.md": "b5afa786b938671e",
   "gsd-core/references/ai-frameworks.md": "425dd69c629230e7",
   "gsd-core/references/artifact-types.md": "218c55caf8aff6df",
@@ -268,7 +269,7 @@
   "gsd-core/workflows/audit-fix.md": "c7878f1dff04adf1",
   "gsd-core/workflows/audit-milestone.md": "99f0b884c9208dde",
   "gsd-core/workflows/audit-uat.md": "e530acf37fd9c699",
-  "gsd-core/workflows/autonomous.md": "dacf6c73407fe29c",
+  "gsd-core/workflows/autonomous.md": "5d4373ad0a20f69b",
   "gsd-core/workflows/check-todos.md": "42806d03eacf9ff6",
   "gsd-core/workflows/cleanup.md": "daca0c4f1d531a02",
   "gsd-core/workflows/code-review-fix.md": "618c850533bd5c9e",