refactor: enforce strict linting and type checking across codebase

- Expand ruff rules (B, S, SIM, RET, COM, C4, G, PT, PIE, T20, DTZ, ICN, TCH, RUF, ANN)
- Switch pyright to strict mode with relaxed test environment
- Replace try-except-pass with contextlib.suppress throughout
- Move type-only imports into TYPE_CHECKING blocks
- Replace ambiguous Unicode chars (en dash, multiplication sign, Greek alpha) with ASCII
- Move color-matcher from base deps to [gpu], remove unused requests dep
- Add pyright to dev deps, update dependabot to uv ecosystem
- Fix hardcoded version in test_version, unused unpacked vars in tests
- Update maintain.sh, CLAUDE.md, .gitignore, .claude/settings.json
- Remove obsolete .agents/rules/project.md
- Upgrade all dependencies (Pygments vulnerability fix)

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

.github/dependabot.yml

@@ -1,21 +1,29 @@
 version: 2
 
 updates:
-  - package-ecosystem: "pip"
+  - package-ecosystem: "uv"
     directory: "/"
     schedule:
       interval: "weekly"
-    commit-message:
-      prefix: "deps"
+    open-pull-requests-limit: 10
     labels:
       - "dependencies"
-    open-pull-requests-limit: 10
+      - "python"
+    groups:
+      minor-and-patch:
+        update-types:
+          - "minor"
+          - "patch"
 
   - package-ecosystem: "github-actions"
     directory: "/"
     schedule:
       interval: "weekly"
-    commit-message:
-      prefix: "ci"
+    open-pull-requests-limit: 5
     labels:
-      - "ci"
+      - "dependencies"
+      - "github-actions"
+    groups:
+      actions:
+        patterns:
+          - "*"