fix: resolve command references per integration type (dot vs hyphen) (#2354)

* fix: resolve command references per integration type (dot vs hyphen)

Replace hardcoded /speckit.<cmd> references in templates with
__SPECKIT_COMMAND_<NAME>__ placeholders that are resolved at
setup time based on the integration type:

- Markdown/TOML/YAML agents: separator='.' → /speckit.plan
- Skills agents: separator='-' → /speckit-plan

Changes:
- Add resolve_command_refs() static method to IntegrationBase
- Add invoke_separator class attribute (.  for base, - for skills)
- Wire into process_template() as step 8
- Update _install_shared_infra() to process page templates
- Replace /speckit.* in 5 command templates and 3 page templates
- Add unit tests for resolve_command_refs (positive + negative)
- Add integration tests verifying on-disk content for all agents
- Add end-to-end CLI tests for Claude (skills) and Copilot (markdown)

Fixes #2347

* review: use effective_invoke_separator() for Copilot skills mode

Address PR review feedback: instead of bleeding _skills_mode
knowledge into the CLI layer, add effective_invoke_separator()
method to IntegrationBase that accepts parsed_options.

CopilotIntegration overrides it to return "-" when skills
mode is requested. The CLI layer simply asks the integration
for its separator — no hasattr or _skills_mode coupling.

Also adds tests for the new method on both base and Copilot,
plus an end-to-end test for 'specify init --integration copilot
--integration-options --skills' verifying page templates get
hyphen refs.

* fix: build_command_invocation preserves full suffix for extension commands

Previously rsplit('.', 1)[-1] on 'speckit.git.commit' yielded
just 'commit', producing /speckit.commit instead of
/speckit.git.commit (or /speckit-git-commit for skills).

Fix: strip only the 'speckit.' prefix when present, then join
remaining segments with the appropriate separator.

Updated in IntegrationBase, SkillsIntegration, and
CopilotIntegration. Added tests for extension commands in
build_command_invocation across all three.

* fix: Copilot dispatch_command() preserves full extension command suffix

dispatch_command() had the same rsplit('.', 1)[-1] bug as
build_command_invocation() — speckit.git.commit would dispatch
as /speckit-commit instead of /speckit-git-commit in skills
mode, or --agent speckit.commit instead of speckit.git.commit
in default mode.

src/specify_cli/integrations/copilot/__init__.py

@@ -103,6 +103,16 @@ class CopilotIntegration(IntegrationBase):
     # Mutable flag set by setup() — indicates the active scaffolding mode.
     _skills_mode: bool = False
 
+    def effective_invoke_separator(
+        self, parsed_options: dict[str, Any] | None = None
+    ) -> str:
+        """Return ``"-"`` when skills mode is requested, ``"."`` otherwise."""
+        if parsed_options and parsed_options.get("skills"):
+            return "-"
+        if self._skills_mode:
+            return "-"
+        return self.invoke_separator
+
     @classmethod
     def options(cls) -> list[IntegrationOption]:
         return [
@@ -145,9 +155,9 @@ class CopilotIntegration(IntegrationBase):
         """
         if self._skills_mode:
             stem = command_name
-            if "." in stem:
-                stem = stem.rsplit(".", 1)[-1]
-            invocation = f"/speckit-{stem}"
+            if stem.startswith("speckit."):
+                stem = stem[len("speckit."):]
+            invocation = "/speckit-" + stem.replace(".", "-")
             if args:
                 invocation = f"{invocation} {args}"
             return invocation
@@ -175,8 +185,8 @@ class CopilotIntegration(IntegrationBase):
         import subprocess
 
         stem = command_name
-        if "." in stem:
-            stem = stem.rsplit(".", 1)[-1]
+        if stem.startswith("speckit."):
+            stem = stem[len("speckit."):]
 
         # Detect skills mode from project layout when not set via setup()
         skills_mode = self._skills_mode
@@ -189,7 +199,7 @@ class CopilotIntegration(IntegrationBase):
                 )
 
         if skills_mode:
-            prompt = f"/speckit-{stem}"
+            prompt = "/speckit-" + stem.replace(".", "-")
             if args:
                 prompt = f"{prompt} {args}"
         else: