[Task]: Rewrite top MOS guide titles for "what is MOS ####" searches #1421

🛠 Description

MOS lookup queries are the site's biggest untapped search surface: about 6,500 impressions at 0.4% CTR (Search Console). People search "what is MOS 0111"; they want a definition first. Our guide titles answer a different question.

Current titles and descriptions (live, from buildGuideMeta in src/containers/career-guide-detail/derive.ts, added in #1354):

Neither says what the MOS is, and neither mentions tech, which is where we want the click to lead.

✅ Acceptance Criteria

• Titles and descriptions for the top 10 MOS guides by impressions are rewritten to match "what is MOS ####" intent, then bridge to software and tech careers. Six are known: 0111, 0231, 0211, 0206, 0204, 0241. Pull the other four from Search Console (pages under /career-guides/, 90 days, sorted by impressions).
• Each title answers the question in plain words (e.g. What Is MOS 0111? Marine Corps Administrative Specialist) and stays under ~60 characters before the site suffix.
• Each description says in one clause what the job is, then names the tech path (e.g. "…and how 0111s move into software engineering"). Under ~155 characters.
• Titles stay unique: __tests__/lib/career-guides.test.ts (the [Task]: Career guide titles collide — 2,905 of 4,202 share a title #1354 uniqueness check) keeps passing.
• Baseline impressions and CTR for each of the 10 pages are recorded in the PR, so the change can be measured in 4 weeks.

📋 Implementation Notes

• Prefer an override map (e.g. src/data/career-guide-meta-overrides.json, keyed by guide slug) that buildGuideMeta checks first, over changing the template for all 4,202 guides. Measure the 10, then decide whether to generalize the template.
• The JSON-LD Occupation.name and description ([Task]: Career guides emit generic WebPage schema instead of Occupation #1356) read from the same meta; check they still read well.
• Estimate: ~2 hours.

🔗 Related Issues or PRs

• [Task]: Career guide titles collide — 2,905 of 4,202 share a title #1354 (title uniqueness), [Task]: Career guides emit generic WebPage schema instead of Occupation #1356 (Occupation schema), [Task]: Make the 4,202 career guides discoverable and cheap to render #1277 (prerender set from Search Console)