Implement /speckit.converge command

Add the built-in converge command that assesses the codebase against a
feature's spec.md, plan.md, and tasks.md and appends remaining unbuilt work
as new traceable tasks to tasks.md (append-only; no git, no change tracking).

- templates/commands/converge.md: full command body (load artifacts, assess
  code, classify findings missing/partial/contradicts/unrequested, append
  '## Phase N — Convergence' tasks with source-ref + gap-type, read-only
  guardrails, converged branch, handoff, before/after_converge hooks)
- Register converge as a core command across all enumeration sites
  (SKILL_DESCRIPTIONS, _FALLBACK_CORE_COMMAND_NAMES, ARGUMENT_HINTS, and the
  integration test command lists incl. copilot/generic file inventories)
- init.py Next Steps panel + README Core Commands table
- tasks.md: T001-T024 complete (T025 manual quickstart pending)

Full suite green: 2343 passed.

src/specify_cli/__init__.py

@@ -429,6 +429,7 @@ SKILL_DESCRIPTIONS = {
     "plan": "Generate technical implementation plans from feature specifications.",
     "tasks": "Break down implementation plans into actionable task lists.",
     "implement": "Execute all tasks from the task breakdown to build the feature.",
+    "converge": "Assess the codebase against spec.md, plan.md, and tasks.md and append remaining work as new tasks.",
     "analyze": "Perform cross-artifact consistency analysis across spec.md, plan.md, and tasks.md.",
     "clarify": "Structured clarification workflow for underspecified requirements.",
     "constitution": "Create or update project governing principles and development guidelines.",

src/specify_cli/commands/init.py

@@ -578,6 +578,7 @@ def register(app: typer.Typer) -> None:
         steps_lines.append(f"   {step_num}.3 [cyan]{_display_cmd('plan')}[/] - Create implementation plan")
         steps_lines.append(f"   {step_num}.4 [cyan]{_display_cmd('tasks')}[/] - Generate actionable tasks")
         steps_lines.append(f"   {step_num}.5 [cyan]{_display_cmd('implement')}[/] - Execute implementation")
+        steps_lines.append(f"   {step_num}.6 [cyan]{_display_cmd('converge')}[/] - Assess the codebase and append remaining work as tasks")
 
         steps_panel = Panel("\n".join(steps_lines), title="Next Steps", border_style="cyan", padding=(1, 2))
         console.print()

src/specify_cli/extensions.py

@@ -32,6 +32,7 @@ _FALLBACK_CORE_COMMAND_NAMES = frozenset({
     "analyze",
     "clarify",
     "constitution",
+    "converge",
     "implement",
     "plan",
     "checklist",

src/specify_cli/integrations/claude/__init__.py

@@ -17,6 +17,7 @@ ARGUMENT_HINTS: dict[str, str] = {
     "plan": "Optional guidance for the planning phase",
     "tasks": "Optional task generation constraints",
     "implement": "Optional implementation guidance or task filter",
+    "converge": "Optional feature name to converge",
     "analyze": "Optional focus areas for analysis",
     "clarify": "Optional areas to clarify in the spec",
     "constitution": "Principles or values for the project constitution",