feat: add click-based colorized output with progress events and build timer

- Add click as explicit dependency (already bundled with typer)
- Replace typer.echo calls with click.echo + click.style for colorized output
- Add BuildEvent enum and ProgressCallback to builder for decoupled progress reporting
- Remove direct typer dependency from builder module
- Show per-target status with colored labels (skip/ok/fail/...)
- Display elapsed build time in summary
- Colorize graph and clean command output
- Update CLI tests to match new output format

bulkgen/builder.py

@@ -3,12 +3,12 @@
 from __future__ import annotations
 
 import asyncio
+import enum
 import os
+from collections.abc import Callable
 from dataclasses import dataclass, field
 from pathlib import Path
 
-import typer
-
 from bulkgen.config import (
     ProjectConfig,
     TargetType,
@@ -28,6 +28,25 @@ from bulkgen.state import (
 )
 
 
+class BuildEvent(enum.Enum):
+    """Events emitted during a build for progress reporting."""
+
+    TARGET_SKIPPED = "skipped"
+    TARGET_BUILDING = "building"
+    TARGET_OK = "ok"
+    TARGET_FAILED = "failed"
+    TARGET_DEP_FAILED = "dep_failed"
+    TARGET_NO_PROVIDER = "no_provider"
+
+
+ProgressCallback = Callable[[BuildEvent, str, str], None]
+"""Signature: (event, target_name, detail_message)."""
+
+
+def _noop_callback(_event: BuildEvent, _name: str, _detail: str) -> None:
+    """Default no-op progress callback."""
+
+
 @dataclass
 class BuildResult:
     """Summary of a build run."""
@@ -35,6 +54,7 @@ class BuildResult:
     built: list[str] = field(default_factory=list)
     skipped: list[str] = field(default_factory=list)
     failed: dict[str, str] = field(default_factory=dict)
+    total_targets: int = 0
 
 
 def _resolve_prompt(prompt_value: str, project_dir: Path) -> str:
@@ -118,6 +138,7 @@ async def run_build(
     config: ProjectConfig,
     project_dir: Path,
     target: str | None = None,
+    on_progress: ProgressCallback = _noop_callback,
 ) -> BuildResult:
     """Execute the build.
 
@@ -143,6 +164,11 @@ async def run_build(
     generations = get_build_order(graph)
     target_names = set(config.targets)
 
+    # Count total buildable targets for progress reporting.
+    result.total_targets = sum(
+        1 for gen in generations for n in gen if n in target_names
+    )
+
     for generation in generations:
         targets_in_gen = [n for n in generation if n in target_names]
 
@@ -150,23 +176,28 @@ async def run_build(
         for name in targets_in_gen:
             if _should_skip_failed_dep(name, config, result):
                 result.failed[name] = "Dependency failed"
+                on_progress(BuildEvent.TARGET_DEP_FAILED, name, "Dependency failed")
                 continue
 
             if _is_dirty(name, config, project_dir, state):
-                if not _has_provider(name, providers, result):
+                if not _has_provider(name, providers, result, on_progress):
                     continue
                 dirty_targets.append(name)
             else:
                 result.skipped.append(name)
+                on_progress(BuildEvent.TARGET_SKIPPED, name, "up to date")
 
         if not dirty_targets:
             continue
 
+        for name in dirty_targets:
+            on_progress(BuildEvent.TARGET_BUILDING, name, "")
+
         outcomes = await _build_generation(
             dirty_targets, config, project_dir, providers
         )
 
-        _process_outcomes(outcomes, config, project_dir, state, result)
+        _process_outcomes(outcomes, config, project_dir, state, result, on_progress)
         save_state(state, project_dir)
 
     return result
@@ -207,6 +238,7 @@ def _has_provider(
     target_name: str,
     providers: dict[TargetType, Provider],
     result: BuildResult,
+    on_progress: ProgressCallback = _noop_callback,
 ) -> bool:
     """Check that the required provider is available; record failure if not."""
     target_type = infer_target_type(target_name)
@@ -214,7 +246,9 @@ def _has_provider(
         env_var = (
             "BFL_API_KEY" if target_type is TargetType.IMAGE else "MISTRAL_API_KEY"
         )
-        result.failed[target_name] = f"Missing {env_var} environment variable"
+        msg = f"Missing {env_var} environment variable"
+        result.failed[target_name] = msg
+        on_progress(BuildEvent.TARGET_NO_PROVIDER, target_name, msg)
         return False
     return True
 
@@ -243,12 +277,13 @@ def _process_outcomes(
     project_dir: Path,
     state: BuildState,
     result: BuildResult,
+    on_progress: ProgressCallback = _noop_callback,
 ) -> None:
     """Process build outcomes: record state for successes, log failures."""
     for name, error in outcomes:
         if error is not None:
             result.failed[name] = str(error)
-            typer.echo(f"FAIL: {name} -- {error}", err=True)
+            on_progress(BuildEvent.TARGET_FAILED, name, str(error))
         else:
             target_cfg = config.targets[name]
             model = resolve_model(name, target_cfg, config.defaults)
@@ -266,4 +301,4 @@ def _process_outcomes(
                 project_dir=project_dir,
             )
             result.built.append(name)
-            typer.echo(f"  OK: {name}")
+            on_progress(BuildEvent.TARGET_OK, name, "")