Add Camel DNA origin story page

[davsclaus]

Summary

• Adds a standalone /camel-dna/ page telling the origin story of Apache Camel — from the very first JMS-to-File route in June 2007 to camel run today
• Covers James Strachan's endpoint-processor-endpoint architecture, the ActiveMQ origins, and the SQL SELECT * FROM analogy — ideas so fundamental they outlast every technology shift
• Adds a prominent "The origin story" callout in the "What is Apache Camel" page linking to the DNA page, placed between the patterns section and "Trusted in production" so it stands out

Test plan

• Verify /camel-dna/ page renders correctly
• Verify the "What is Apache Camel" page shows the origin story callout with bold link
• Verify link from what-is-apache-camel to /camel-dna/ works

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