chore(process): add zero-warnings policy to pr-push and pr-review

- pr-push step 1b: lint check before pushing (gdlint, clippy, ruff)
- pr-review step 0c: check warning count before spawning reviewers
- Added .gdlintrc with max-line-length: 120
- Created ticket #783 for Sprint 31: clean up existing 253 warnings
- Updated #780 with edge visibility rule (show edges only for selected system)

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

.claude/skills/pr-push/SKILL.md

@@ -34,7 +34,35 @@ git branch --show-current
 
 If on `main`, stop: "You're on main. Switch to a team branch first."
 
-### 1b. Runtime smoke test (MANDATORY)
+### 1b. Zero warnings policy (MANDATORY)
+
+Before pushing, verify the branch has **zero lint warnings**. Any warning
+must be either fixed or suppressed with a commented justification.
+
+**For client/visual branches:**
+```bash
+gdlint client/scripts/ client/ui/ 2>&1
+```
+
+If warnings remain, fix them before pushing. For warnings that cannot be
+fixed (e.g. intentional long lines in data literals), add a `# gdlint:
+ignore` comment with a reason.
+
+**For server branches:**
+```bash
+cargo clippy -- -D warnings 2>&1
+```
+
+**For CI/tooling branches:**
+```bash
+ruff check tooling/ 2>&1
+```
+
+The goal is zero warnings in the pre-push output. Advisory warnings that
+the pre-push hook reports as "(advisory, not blocking)" should still be
+zero — they are advisory only because we haven't enforced them yet.
+
+### 1c. Runtime smoke test (MANDATORY)
 
 Before pushing, verify the game actually runs. This is non-negotiable —
 Sprint 28 proved that code review without runtime testing misses critical

.claude/skills/pr-review/SKILL.md

@@ -47,6 +47,19 @@ godot --headless --path client --quit 2>&1 | grep -i "SCRIPT ERROR"
 If script errors appear in the branch diff files, flag them immediately
 before spawning reviewers — no point reviewing code that doesn't parse.
 
+### 0c. Zero warnings check
+
+The project enforces a **zero warnings policy**. Before spawning reviewers,
+check if the branch introduces lint warnings:
+
+- **client/visual:** `gdlint client/scripts/ client/ui/` should report 0 issues
+- **server:** `cargo clippy -- -D warnings` should be clean
+- **ci/tooling:** `ruff check tooling/` should be clean
+
+If warnings exist, note the count in the review output. Reviewers should
+flag any **new** warnings introduced by the branch as `warning` severity.
+Pre-existing warnings are not PR blockers but should be tracked for cleanup.
+
 ### 1. Determine the branch to review
 
 If the user provided a branch name as argument, use it. Otherwise list open