feat(cv): add opt-in GDPR consent footer slot ({{CONSENT}})

Problem

EU candidates often need a GDPR consent statement on their CV (e.g., "I consent to the processing of my personal data as described in..."). Currently, CV templates have no footer slot for this — candidates must manually edit HTML or fork templates.

Proposed Solution

Add an opt-in \{\{CONSENT\}\} placeholder to all HTML CV templates, mirroring the existing \{\{PHOTO\}\} slot pattern (#264).

Key properties:

• Empty by default — existing CVs render unchanged
• CSS guard: .cv-consent:empty { display: none; } prevents stray horizontal lines when no consent text
• Payload field: payload.consent (string, optional)
• Templates covered: cv-template.html, resume-template.html, cv-template.{compact,executive,jake,leadership,modern}.html

Precedent

This follows the exact pattern of \{\{PHOTO\}\} (#264):

• Optional slot in templates
• No-op when empty
• Filled from payload
• Same CSS discipline (absent = unchanged layout)

Implementation

• Builder substitution: CONSENT: escapeHtml(payload.consent || '') in renderReport()
• Schema: 'consent' added to KNOWN_ROOT_KEYS.html
• Tests: 70 assertions across 7 templates, covering empty-render, escaping, section-strip survival
• Docs: Updated modes/pdf.md, batch/batch-prompt.md, templates/README.md

Use Case (EU GDPR)

Polish example:

"Wyrażam zgodę na przetwarzanie moich danych osobowych zawartych w aplikacji dla potrzeb niezbędnych do realizacji procesu rekrutacji (zgodnie z ustawą z 10 maja 2018 roku o ochronie danych osobowych i RODO)."

German example:

"Ich willige ein, dass meine personenbezogenen Daten für den Bewerbungsprozess verarbeitet werden gemäß Art. 6 Abs. 1 lit. b DSGVO."

Files Changed

13 files:

• 7 templates (+CSS +footer div)
• 1 test file (70 assertions)
• 3 docs (schema, batch prompt, README)
• 2 builder/schema (wiring)

Checklist

• Tests pass (tests/cv-consent-footer.test.mjs)
• Lint clean
• No user-layer files touched
• Atomic commits (conventional commits style)
• Issue approved by maintainer
• PR submitted (after approval)