feat: publish complete learning pages and MUSA validation

[googs1025]

Summary

• publish all six weeks of learning notes, exercises, completion criteria, records, and a validation dashboard inside GitHub Pages
• record MTT S4000 / MUSA SDK 3.1.0 evidence for 39 targets with explicit PASS, limited, not-run, and build-failure states
• correct device-dependent warp-size guidance and derive shuffle shared-memory allocation from warpSize
• enforce generated-page freshness, manifest integrity, page structure, and local links in CI

Validation results

• 33 PASS
• 2 ENV_LIMITED
• 3 NOT_RUN
• 1 BUILD_FAIL

04_reduce_shfl produced the expected result on the original revision, but review found a hard-coded 128-wide shared allocation. The code now derives this from warpSize; because the validation machine was released before rerunning, the corrected target is honestly marked NOT_RUN.

Test plan

• node scripts/build-pages.js --check
• node --test scripts/build-pages.test.js scripts/check-docs.test.js (47/47)
• node scripts/check-docs.js (154 quiz questions, 39 validation targets, 28 pages, 270 local links)
• git diff --check
• credential/private-key scan
• local HTTP render inspection for home, generated learning, and validation pages