[opencode] Sprint 1: Fix install.sh env var bug, add opencode-status.sh script

[SkyWalker2506]

Sprint 1 Tasks

Based on forge analysis (analysis/MASTER_ANALYSIS.md).

• S1-T1: Fix install.sh — remove OPENCODE_MODEL env var from aliases (doesn't work), use opencode.json config instead
• S1-T2: Create scripts/opencode-status.sh — check CLI installed, Ollama running, config exists, show summary
• S1-T3: Create scripts/opencode-config.sh — read/write ~/.config/opencode/opencode.json safely
• S1-T4: Add set -euo pipefail to install.sh + better error messages
• S1-T5: Add uninstall function to install.sh (--uninstall flag removes aliases from rc)

Priority: P0 critical — env var bug causes broken aliases for all users
Estimated effort: 2-3 hours total