211 (#321)

* #211 feat: add real-world examples directory with 4 comprehensive examples

Created examples/ directory with real-world service examples demonstrating
masterror integration with popular frameworks:

- axum-rest-api: Full REST API with RFC 7807 Problem Details, domain errors,
  metadata attachment, and 11 integration tests
- sqlx-database: Database error handling patterns including connection errors,
  constraint violations, and transactions
- custom-domain-errors: Payment processing domain with derive macro usage,
  showcasing authentication, validation, and external service errors
- basic-async: Async error handling with tokio, timeout conversion, and
  error propagation patterns

All examples include:
- Comprehensive README.md documentation
- Runnable source code with cargo run
- Integration tests where applicable
- SPDX license headers
- publish = false in Cargo.toml

Updated:
- examples/README.md: Index of all examples with running instructions
- README.template.md: Added Examples section with table
- README.md: Regenerated from template
- Cargo.toml: Added 4 examples as workspace members

Closes #211

* #211 fix: add Unicode-3.0 to allowed licenses for ICU dependencies

* #211 chore: add cargo deny to pre-commit hook and install script

Added cargo deny check to pre-commit hook to catch license issues locally
before CI. This prevents CI failures like the Unicode-3.0 license issue.

Changes:
- Added cargo deny check (advisories, bans, licenses, sources) to pre-commit
- Created .github/scripts/pre-commit (version-controlled hook)
- Created .github/scripts/install-hooks.sh (automated installation)
- Updated deny.toml to allow OSI-approved licenses:
  - Unicode-3.0 (ICU dependencies)
  - BSD-3-Clause (encoding_rs, matchit)
  - Zlib (foldhash)

Pre-commit now runs all CI checks locally:
- rustfmt (nightly)
- REUSE compliance
- clippy (all features, all targets)
- tests (all features)
- cargo audit
- cargo deny (NEW) - catches license issues before CI
- README.md generation

This significantly reduces CI failures by catching issues locally.

Author: RAprogramm

.github/scripts/install-hooks.sh

@@ -0,0 +1,30 @@
+#!/usr/bin/env bash
+# SPDX-FileCopyrightText: 2025 RAprogramm <[email protected]>
+#
+# SPDX-License-Identifier: MIT
+
+set -euo pipefail
+
+REPO_ROOT="$(git rev-parse --show-toplevel)"
+HOOKS_DIR="$REPO_ROOT/.git/hooks"
+PRE_COMMIT_SCRIPT="$REPO_ROOT/.github/scripts/pre-commit"
+
+if [ ! -f "$PRE_COMMIT_SCRIPT" ]; then
+  echo "Error: pre-commit script not found at $PRE_COMMIT_SCRIPT"
+  exit 1
+fi
+
+echo "Installing pre-commit hook..."
+cp "$PRE_COMMIT_SCRIPT" "$HOOKS_DIR/pre-commit"
+chmod +x "$HOOKS_DIR/pre-commit"
+
+echo "✅ Pre-commit hook installed successfully!"
+echo ""
+echo "The hook will run the following checks before each commit:"
+echo "  - rustfmt (nightly)"
+echo "  - REUSE compliance"
+echo "  - clippy (all features, all targets)"
+echo "  - tests (all features)"
+echo "  - cargo audit"
+echo "  - cargo deny (advisories, bans, licenses, sources)"
+echo "  - README.md generation"

.github/scripts/pre-commit

@@ -0,0 +1,66 @@
+#!/usr/bin/env bash
+# SPDX-FileCopyrightText: 2025 RAprogramm <[email protected]>
+#
+# SPDX-License-Identifier: MIT
+
+set -euo pipefail
+
+echo "🔧 Ensuring nightly rustfmt is available..."
+if ! rustup toolchain list | grep -q "^nightly"; then
+  rustup toolchain install nightly >/dev/null
+fi
+rustup component add rustfmt --toolchain nightly >/dev/null
+
+echo "🧹 Checking formatting with rustfmt..."
+cargo +nightly fmt --all -- --check
+
+echo "📜 Checking REUSE compliance..."
+if command -v reuse &> /dev/null; then
+    reuse lint
+else
+    echo "⚠️  Warning: reuse tool not installed, skipping license compliance check"
+    echo "   Install with:"
+    echo "   - Arch Linux: paru -S reuse (or sudo pacman -S reuse)"
+    echo "   - pip:        pip install reuse"
+fi
+
+echo "🔍 Running clippy (all features, all targets)..."
+cargo clippy --workspace --all-targets --all-features -- -D warnings
+
+echo "🧪 Running tests (all features)..."
+cargo test -vv
+
+echo "🛡️ Running cargo audit..."
+if ! command -v cargo-audit >/dev/null 2>&1; then
+  cargo install --locked cargo-audit >/dev/null
+fi
+cargo audit
+
+echo "🔒 Running cargo deny..."
+if ! command -v cargo-deny >/dev/null 2>&1; then
+  echo "Installing cargo-deny..."
+  cargo install --locked cargo-deny --version 0.18.4 >/dev/null
+fi
+cargo deny check advisories bans licenses sources
+
+# Uncomment if you want to validate SQLx offline data
+# echo "📦 Validating SQLx prepare..."
+# cargo sqlx prepare --check --workspace
+
+# same deterministic env
+export TZ=UTC
+export LC_ALL=C.UTF-8
+export NO_COLOR=1
+export CARGO_TERM_COLOR=never
+export SOURCE_DATE_EPOCH=0
+
+# Generate
+./.github/scripts/gen_readme.sh
+
+# Stage README if changed
+if ! git diff --quiet -- README.md; then
+  git add README.md
+fi
+
+echo "✅ All checks passed!"
+