Config: re-evaluate `defaultConfig` `enabled: true` defaults for fresh deployments

[lonix]

Problem

src/services/config-schema.ts defaultConfig has several feature .enabled: true defaults. With #438 ("setup wizard starts blank"), the wizard no longer pre-checks these — but the underlying runtime defaults still mean a fresh bot starts with several features active before the operator has run the wizard.

Examples observed in the audit:

• voicechannels.controlpanel.enabled: true
• quotes.header_enabled: true, quotes.header_pin_enabled: true
• achievements.announcements.enabled: true, achievements.dm_notifications.enabled: true
• notices.header_enabled: true, notices.header_pin_enabled: true

Some defaults are sensible (e.g., quotes.header_pin_enabled is moot unless quotes.enabled — which defaults false — is also flipped). Others might surprise a fresh-install operator.

Proposed change

• Audit every enabled: true default in defaultConfig.
• For each: decide whether a fresh bot should ship with it on or off, given that the operator hasn't yet run the wizard.
• Default principle: if the parent feature defaults to false, sub-feature defaults can stay true (they're gated and inert). If a feature is independently runtime-active when true, default to false — opt-in is consistent with WebUI: setup wizard should start with no features pre-selected #438.
• Apply changes; add a short comment in defaultConfig documenting the principle so future additions stay consistent.

Acceptance

• Audit summary in PR body or docs/ note.
• defaultConfig updated per decisions.
• Test asserts the matrix (every .enabled boolean default, expected value).

Notes

• Pairs with WebUI: setup wizard should start with no features pre-selected #438 — same "fresh install starts off, operator opts in" philosophy at the runtime layer.