feat: add Factory Droid CLI integration (#822) (#3587)

Adds a skills-based integration for the Factory Droid CLI alongside the
existing Claude/Codex skills agents. The integration scaffolds
`.factory/skills/speckit-*` directories and documents the install step
in the devcontainer post-create script via the official npm
distribution (`npm install -g droid`), which matches the layout of every
other CLI install block above and avoids executing an unverified remote
shell installer. The integration is also added to the user-facing
supported-agent table in `docs/reference/integrations.md` so the new key
is discoverable from the published documentation, as required by the
"Updating this documentation" guideline in AGENTS.md.

Operator-supplied extra args via `SPECKIT_INTEGRATION_DROID_EXTRA_ARGS`
are appended after the canonical Spec Kit flags so the canonical flags
are always present in argv. The Factory Droid CLI parser uses
last-wins duplicate-flag semantics (verified empirically against
droid 0.175.0), so a later operator-supplied value may override the
canonical one — this is a deliberate inversion of the cursor-agent /
opencode / codex ordering.

Includes:
- `src/specify_cli/integrations/droid/__init__.py` (subpackage)
- `tests/integrations/test_integration_droid.py` (46 tests, including
  regression coverage for the no-trailing-newline frontmatter fusion
  bug, idempotent skill injection, and env-var path resolution)
- `integrations/catalog.json` entry + `updated_at` bump
- Alphabetical registration in `src/specify_cli/integrations/__init__.py`
  and `tests/integrations/test_registry.py`
- Devcontainer Droid install block via the npm distribution
  (`npm install -g droid`), replacing the earlier curl-based installer
- User-facing supported-agent table row in
  `docs/reference/integrations.md` (key `droid`, `.factory/skills/`
  layout, `/speckit-<command>` invocation)
- `AGENT_CONFIG` entry and matching alphabetical entries in
  `tests/test_agent_config_consistency.py` (`ISSUE_TEMPLATE_AGENT_KEYS`)
  and the three issue-template dropdowns (`agent_request.yml`,
  `bug_report.yml`, `feature_request.yml`) so
  `test_issue_template_agent_lists_match_runtime_integrations` keeps
  the runtime/template surfaces synchronized

Closes #822

Assisted-by: Droid (oracle-reviewer)

Assisted-by: Droid (model: MiniMax M3, autonomous)

Co-authored-by: factory-droid[bot] <138933559+factory-droid[bot]@users.noreply.github.com>

.github/ISSUE_TEMPLATE/agent_request.yml

@@ -8,7 +8,7 @@ body:
       value: |
         Thanks for requesting a new agent! Before submitting, please check if the agent is already supported.
 
-        **Currently supported agents**: Amp, Antigravity, Auggie CLI, Claude Code, Cline, CodeBuddy, Codex CLI, Cursor, Devin for Terminal, Firebender, Forge, Gemini CLI, GitHub Copilot, Goose, Grok Build, Hermes Agent, IBM Bob, Junie, Kilo Code, Kimi Code, Kiro CLI, Lingma, Mistral Vibe, Oh My Pi, opencode, Pi Coding Agent, Qoder CLI, Qwen Code, RovoDev ACLI, SHAI, Tabnine CLI, Trae, ZCode, Zed
+        **Currently supported agents**: Amp, Antigravity, Auggie CLI, Claude Code, Cline, CodeBuddy, Codex CLI, Cursor, Devin for Terminal, Factory Droid, Firebender, Forge, Gemini CLI, GitHub Copilot, Goose, Grok Build, Hermes Agent, IBM Bob, Junie, Kilo Code, Kimi Code, Kiro CLI, Lingma, Mistral Vibe, Oh My Pi, opencode, Pi Coding Agent, Qoder CLI, Qwen Code, RovoDev ACLI, SHAI, Tabnine CLI, Trae, ZCode, Zed
 
   - type: input
     id: agent-name

.github/ISSUE_TEMPLATE/bug_report.yml

@@ -71,6 +71,7 @@ body:
         - Codex CLI
         - Cursor
         - Devin for Terminal
+        - Factory Droid
         - Firebender
         - Forge
         - Gemini CLI

.github/ISSUE_TEMPLATE/feature_request.yml

@@ -65,6 +65,7 @@ body:
         - Codex CLI
         - Cursor
         - Devin for Terminal
+        - Factory Droid
         - Firebender
         - Forge
         - Gemini CLI