feat: ring shapes, auth reuse, input tests, README docs, CI improvements

- Add --ring-shape (circle/square/diamond/hexagon/pill) with geometry module
- Reuse PAM context across auth attempts (no reload per-keystroke)
- Proper error propagation in screenshot effects (unwrap → Result + context)
- Remove theme presets (modern/pixel/glass) and --theme flag
- Add input cooldown after failed attempt (400ms debounce)
- Add Ctrl+held peek password, Home/End/Delete cursor keys
- Add all input unit tests (23 new tests)
- Add --max-dots, feedback duration, timeout, interval config options
- Add --log-path, --auth-timeout, verifying_color config fields
- Remove unused deps: futures, gio, env_logger, num-traits, thiserror, bytemuck
- Fix media bar: remove stop button, fix art+text overlap, uniform hit areas
- Fix CI: source-only releases, nightly prereleases, dependabot groups, labeler paths
- Update issue templates with structured forms
- Add stale workflow for inactive issues/PRs
- Update README: full options table (28 flags), remove theme docs, add shapes

.github/dependabot.yml

@@ -1,5 +1,3 @@
-# Dependabot configuration for RustLock
-
 version: 2
 
 updates:
@@ -19,6 +17,13 @@ updates:
     reviewers:
       - "JorySeverijnse"
     versioning-strategy: "increase"
+    groups:
+      rust-dependencies:
+        patterns:
+          - "*"
+        update-types:
+          - "minor"
+          - "patch"
 
   - package-ecosystem: "github-actions"
     directory: "/"
@@ -29,4 +34,11 @@ updates:
       timezone: "UTC"
     labels:
       - "dependencies"
-      - "github-actions"
+      - "github-actions"
+    groups:
+      actions-dependencies:
+        patterns:
+          - "*"
+        update-types:
+          - "minor"
+          - "patch"