docs: complete project documentation and Gitea CI setup

Add STATUS.md (what's done, verification, future work), GITEA.md (act_runner,
master branch policy, pipeline), and CONTRIBUTING.md (dev guide, new language
checklist). Update README for all 28 validators, docs index, and project tree.

Align Gitea Actions with master as default branch; add PR and issue templates.
Expand .gitignore for debug artifacts and test binaries.

.gitea/ISSUE_TEMPLATE/bug_report.yaml

@@ -0,0 +1,43 @@
+name: Bug report
+description: Validation error, hang, or incorrect detection
+labels: [bug]
+body:
+  - type: markdown
+    attributes:
+      value: |
+        Include a minimal repro. If nimcheck hangs, note that — likely a tokenizer loop.
+  - type: textarea
+    id: repro
+    attributes:
+      label: Minimal source or file path
+      placeholder: paste code or path
+    validations:
+      required: true
+  - type: dropdown
+    id: flavor
+    attributes:
+      label: Language flavor
+      options:
+        - auto-detect
+        - nim
+        - python
+        - bash
+        - javascript
+        - typescript
+        - other
+  - type: textarea
+    id: expected
+    attributes:
+      label: Expected result
+    validations:
+      required: true
+  - type: textarea
+    id: actual
+    attributes:
+      label: Actual result
+    validations:
+      required: true
+  - type: input
+    id: nim_version
+    attributes:
+      label: Nim version (`nim --version`)