docs(ecosystem): add opencode-terminal to plugins section

[ShivamChavan01]

Issue for this PR

N/A - docs-only ecosystem addition. Docs PRs are exempt from the linked-issue requirement (pr-standards.yml skips docs/refactor/feat).

Type of change

• Bug fix
• New feature
• Refactor / code improvement
• Documentation

What does this PR do?

Adds opencode-terminal to the Plugins table on the ecosystem page. One table row added.

opencode-terminal is my open-source plugin (npm: opencode-terminal@0.2.0). Users install it via "plugin": ["opencode-terminal"] in opencode.json - same npm mechanism as the other listed plugins. It gives OpenCode a native OS terminal plus persistent background sessions with auto-detect, REPL input, and process tree control. The ecosystem page invites community projects to submit PRs, so here it is.

How did you verify your code works?

Docs-only change, plus verified the linked plugin itself works from a clean install:

1. npm view opencode-terminal - 0.2.0 live, repo/homepage point to the new opencode-terminal repo name.
2. Fresh npm i opencode-terminal@0.2.0 in an empty dir, imported TerminalPlugin with bun - all 9 tools register: open_terminal, terminal_detect, close_terminal, terminal_run, terminal_start, terminal_log, terminal_send, terminal_kill, terminal_list.
3. Executed terminal_detect from the installed package - returns valid detection JSON.
4. tsc --noEmit passes on the plugin source.
5. Table row matches existing column width (203 chars, same as neighboring rows).

Screenshots / recordings

ezgif-72cb9da3fa3aedc5.mp4

No UI change - one markdown table row added.

Checklist

• I have tested my changes locally
• I have not included unrelated changes in this PR