fix(hooks): remove unsupported prompt-type SessionStart hook; convert PostCompact to command

[jfcvb68nbb-max]

Fixes the SessionStart: prompt-type hooks are not supported startup error (tracked in #93 and ~10 duplicates: #125, #116, #106, #97, #96, #87, #61, #40, #29).

Problem

hooks/hooks.json declares type: "prompt" hooks that the Claude Code / Codex harness rejects — prompt hooks require conversation context, which these events don't provide:

• SessionStart — 3rd hook is prompt-type → printed as a startup error every session.
• PostCompact — its only hook is prompt-type → the whole block is dropped, so wiki/hot.md is never re-read after a compaction (the feature silently never worked).

Fix

• SessionStart: delete the prompt hook. It was redundant — the first command hook ([ -f wiki/hot.md ] && cat wiki/hot.md) already prints that context to stdout.
• PostCompact: convert the prompt hook to the same command form, so hot-cache restoration actually fires after compaction.

No behavior lost: hot.md still restores on both SessionStart and PostCompact, now via command hooks that print to stdout. PostToolUse and Stop hooks are untouched.

Validation

• hooks/hooks.json parses as valid JSON.
• SessionStart types → ["command","command"]; PostCompact → ["command"]; zero prompt-type hooks remain.
• Reproduced and verified the fix on Windows 11 (Claude Code + Codex CLI); the original reporter saw it on WSL2 — platform-independent.