chore: retire iflow integration — product discontinued (#3166) (#3211)

Remove the iFlow CLI integration whose product was shut down: subpackage,
registry entry, catalog entry, docs, tests, and issue-template options.

Assisted-by: GitHub Copilot (model: Claude Opus 4.8, autonomous)

Co-authored-by: Copilot <223556219+Copilot@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, Hermes Agent, IBM Bob, iFlow CLI, Junie, Kilo Code, Kimi Code, Kiro CLI, Lingma, Mistral Vibe, Oh My Pi, opencode, Pi Coding Agent, Qoder CLI, Qwen Code, Roo Code, RovoDev ACLI, SHAI, Tabnine CLI, Trae, Windsurf, ZCode, Zed
+        **Currently supported agents**: Amp, Antigravity, Auggie CLI, Claude Code, Cline, CodeBuddy, Codex CLI, Cursor, Devin for Terminal, Firebender, Forge, Gemini CLI, GitHub Copilot, Goose, 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, Roo Code, RovoDev ACLI, SHAI, Tabnine CLI, Trae, Windsurf, ZCode, Zed
 
   - type: input
     id: agent-name

.github/ISSUE_TEMPLATE/bug_report.yml

@@ -78,7 +78,6 @@ body:
         - Goose
         - Hermes Agent
         - IBM Bob
-        - iFlow CLI
         - Junie
         - Kilo Code
         - Kimi Code

.github/ISSUE_TEMPLATE/feature_request.yml

@@ -72,7 +72,6 @@ body:
         - Goose
         - Hermes Agent
         - IBM Bob
-        - iFlow CLI
         - Junie
         - Kilo Code
         - Kimi Code