feat: implement all P1/P2/P3/P4 improvements from issue backlog

P1 correctness:
- filter test files by default (--include-tests to opt in)
- per-module diagrams show cross-module dependency arrows
- qualified type names (Module::TypeName) fix false edges from duplicate names

P2 output richness:
- method parameter types and return types in class diagrams (Rust + Python)
- Python pyproject.toml project analyzer (--level project for monorepos)

P3 unique value:
- boundary rules in archlens.toml ([rules] allow/deny, --strict enforcement)

P4 nice to have:
- dependency weight labels on module arrows (--no-weights to disable)
- --watch mode with 500ms debounce
- D2 renderer adapter (--format d2)
- interactive self-contained HTML viewer (--format html)
- git-aware incremental analysis (--since <ref>)

README.md

@@ -2,7 +2,7 @@
 
 Generate architecture diagrams from source code. Runs on CI to keep docs fresh.
 
-Supports Rust and Python. Produces Mermaid or ASCII output.
+Supports Rust, Python and C# (planned). Produces Mermaid, D2, ASCII, or interactive HTML output.
 
 ## Install
 
@@ -28,6 +28,12 @@ archlens . --output docs/architecture.mmd
 # Split by module (one file per module + overview)
 archlens . --level type --split-by-module --output docs/arch/
 
+# D2 format
+archlens . --format d2 --output docs/architecture.d2
+
+# Interactive HTML viewer
+archlens . --format html --output docs/architecture.html
+
 # ASCII output to terminal
 archlens . --format ascii
 
@@ -37,6 +43,18 @@ archlens . --scope src/domain
 # Exclude directories
 archlens . --exclude tests/ --exclude generated/
 
+# Exclude test files from diagrams (default: excluded)
+archlens . --include-tests
+
+# Show/hide dependency weights on module arrows (default: shown)
+archlens . --level module --no-weights
+
+# Watch for changes and regenerate automatically
+archlens . --watch
+
+# Analyse only files changed since a git ref (useful in CI)
+archlens . --since HEAD~1
+
 # Verbose logging
 archlens . -v    # info
 archlens . -vv   # debug
@@ -50,7 +68,13 @@ Check if committed diagrams are up to date:
 archlens . --level project --check --output docs/architecture.mmd
 ```
 
-Exit code 1 if the diagram has changed. Use `--strict` to also fail on parse warnings.
+Exit code 1 if the diagram has changed. Use `--strict` to also fail on parse warnings or boundary rule violations.
+
+Only re-analyse files changed since the last release tag:
+
+```bash
+archlens . --since v1.2.0 --output docs/architecture.mmd
+```
 
 Compare current state against an existing file:
 
@@ -80,23 +104,41 @@ level = "module"
 format = "mermaid"
 # path = "docs/architecture.mmd"
 split_by_module = false
+
+[rules]
+# Allowed dependency directions — unlisted directions are violations
+# allow = ["Application --> Domain", "Adapters --> Domain"]
+
+# Explicitly forbidden directions — always checked
+# deny = ["Domain --> Adapters", "Domain --> Application"]
 ```
 
+Violations are printed to stderr. Pass `--strict` to exit with code 1 on any violation.
+
 ## Diagram Levels
 
 | Level | What it shows | Source |
 |-------|--------------|--------|
-| `project` | Crate/package dependencies | `Cargo.toml` |
-| `module` | Module-level dependency graph | Imports + manifest deps |
-| `type` | Class diagram with fields, methods, relationships | Source code (tree-sitter) |
+| `project` | Crate/package dependencies | `Cargo.toml` or `pyproject.toml` |
+| `module` | Module-level dependency graph with coupling weights | Imports + manifest deps |
+| `type` | Class diagram with fields, methods, signatures, relationships | Source code (tree-sitter) |
+
+## Output Formats
+
+| Format | Flag | Extension | Notes |
+|--------|------|-----------|-------|
+| Mermaid | `--format mermaid` | `.mmd` | Default. Renders in GitHub, GitLab, Obsidian |
+| D2 | `--format d2` | `.d2` | Better layout control, renders to SVG |
+| ASCII | `--format ascii` | `.txt` | Terminal-friendly |
+| HTML | `--format html` | `.html` | Self-contained interactive viewer, clickable nodes |
 
 ## Supported Languages
 
-| Language | Types | Inheritance | Composition | Imports |
-|----------|-------|-------------|-------------|---------|
-| Rust | struct, enum, trait | `impl Trait for Type` | struct fields | `use`, `mod` |
-| Python | class | `class Foo(Bar)` | `__init__` params, type annotations | `import`, `from ... import` |
-| C# | planned | - | - | - |
+| Language | Types | Inheritance | Composition | Imports | Method signatures |
+|----------|-------|-------------|-------------|---------|-------------------|
+| Rust | struct, enum, trait | `impl Trait for Type` | struct fields | `use`, `mod` | params + return type |
+| Python | class | `class Foo(Bar)` | `__init__` params, type annotations | `import`, `from ... import` | typed params + return annotation |
+| C# | planned | - | - | - | - |
 
 ## Architecture
 
@@ -104,18 +146,21 @@ Built with hexagonal architecture (ports and adapters) + DDD.
 
 ```
 crates/
-  domain/           # Core model, zero external deps
-  application/      # Use cases, orchestration
+  domain/             # Core model, zero external deps
+  application/        # Use cases, orchestration
   adapters/
-    tree-sitter/    # Source code parsing (Rust, Python)
-    cargo-workspace/ # Cargo.toml dependency extraction
-    walkdir/        # File discovery
-    mermaid/        # Mermaid diagram output
-    ascii/          # Terminal output
-    file-writer/    # Write to disk
-    stdout-writer/  # Write to stdout
-    toml-config/    # Config file parsing
-  presentation/     # CLI (clap), composition root
+    tree-sitter/      # Source code parsing (Rust, Python)
+    cargo-workspace/  # Cargo.toml dependency extraction
+    python-project/   # pyproject.toml dependency extraction
+    walkdir/          # File discovery
+    mermaid/          # Mermaid diagram output
+    d2/               # D2 diagram output
+    ascii/            # Terminal output
+    html-viewer/      # Interactive HTML output
+    file-writer/      # Write to disk
+    stdout-writer/    # Write to stdout
+    toml-config/      # Config file parsing
+  presentation/       # CLI (clap), composition root
 ```
 
 ## License