feat(ci): autonomous Dependabot auto-fix and auto-merge workflows (#263)

Makes Dependabot fully hands-off: red PRs get auto-fixed, green PRs get
approved and auto-merged on my behalf. Closes #262.

Two workflows:
- `dependabot-autofix.md` (gh-aw agentic, copilot engine) — fires on CI
failure for a `dependabot/**` branch, reproduces the failure, and pushes
a minimal behavior-preserving fix. Read-only agent job;
`agent-fixed`/`needs-human` loop guard; `github-actions` bumps route to
`needs-human` (can't push `.github/workflows/**` with GITHUB_TOKEN).
- `dependabot-automerge.yml` — fires on green CI for a `dependabot/**`
branch, approves as a CODEOWNER and enables native GitHub auto-merge.

Required secrets (already added): `DEPENDABOT_MERGE_PAT`,
`GH_AW_CI_TRIGGER_TOKEN`. `combine-prs` was disabled to avoid overlap.

```mermaid
flowchart TD
    A[Dependabot opens/updates PR] --> B[CI runs]
    B -->|green| C[dependabot-automerge]
    C --> D[Approve as CODEOWNER + enable auto-merge]
    D --> E[Merges once all required checks pass]
    B -->|red| F[dependabot-autofix agent]
    F --> G{Fixable?}
    G -->|yes| H[Push minimal fix + label agent-fixed]
    H --> B
    G -->|no / still red| I[Label needs-human + comment]
```

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

Author: dorlugasigal

.github/aw/actions-lock.json

@@ -1,14 +1,24 @@
 {
   "entries": {
+    "actions/checkout@v6": {
+      "repo": "actions/checkout",
+      "version": "v6",
+      "sha": "df4cb1c069e1874edd31b4311f1884172cec0e10"
+    },
     "actions/github-script@v8": {
       "repo": "actions/github-script",
       "version": "v8",
       "sha": "ed597411d8f924073f98dfc5c65a23a2325f34cd"
     },
-    "github/gh-aw-actions/setup@v0.64.2": {
-      "repo": "github/gh-aw-actions/setup",
-      "version": "v0.64.2",
-      "sha": "f22886a9607f5c27e79742a8bfc5faa34737138b"
+    "actions/github-script@v9": {
+      "repo": "actions/github-script",
+      "version": "v9",
+      "sha": "373c709c69115d41ff229c7e5df9f8788daa9553"
+    },
+    "actions/setup-node@v6": {
+      "repo": "actions/setup-node",
+      "version": "v6",
+      "sha": "48b55a011bda9f5d6aeb4c2d9c7362e8dae4041e"
     }
   }
 }