fix(hooks): use object schema in hooks.json across vertical plugins

[darwin7381]

Summary

• hooks/hooks.json ships as an empty array ([]) in 4 vertical plugins (financial-analysis, equity-research, private-equity, wealth-management), but Claude Code's plugin loader validates the file against an object schema and rejects with Invalid input: expected object, received array.
• Aligns the four affected plugins with the working {\"hooks\": {}} format already used by investment-banking.

Reproduction

Captured via `claude --debug-file `:
```
[ERROR] Failed to load hooks for financial-analysis: [
[ERROR] Failed to load hooks for wealth-management: [
[ERROR] Failed to load hooks for private-equity: [
[ERROR] Failed to load hooks for equity-research: [
[DEBUG] Plugin not available for MCP: ... - error type: hook-load-failed
```

Also reproducible via `claude plugin validate `:
```
✘ Found 1 error:
❯ root: Invalid input: expected object, received array
✘ Validation failed
```

Consequences before fix

• Plugins show as "failed to load" in `claude plugin list`
• Bundled MCP servers (FactSet, S&P, Daloopa, Morningstar, etc.) are disabled (`hook-load-failed` error type)
• Skills and slash commands degrade — Claude falls back to LLM-inferred workflows rather than the canonical plugin skills, producing similar-looking but materially different outputs (e.g., no `thesis-tracker` pillar-weight discipline, no `pitch-deck` .pptx template phase)

After fix

• `claude plugin validate` → `✔ Validation passed` for all four plugins
• No more `Failed to load hooks` errors in startup log
• Plugins report enabled in `claude plugin list`
• MCP servers and skills load as designed

Test plan

• Ran `claude plugin validate plugins/vertical-plugins/{financial-analysis,equity-research,private-equity,wealth-management}` — all four pass
• Ran `claude --debug-file` and confirmed no `Failed to load hooks` for the four plugins
• Verified `investment-banking/hooks/hooks.json` already uses the same `{"hooks": {}}` format and loads cleanly

🤖 Generated with Claude Code