feat: fix dynamic devfile for non-containerfile repos, add factory URL and Dev Spaces docs

[jflowers]

Summary

Addresses all three gaps identified in Issue #5:

• Dynamic devfile install fix: Replaced local /projects/scripts/install-uf-tools.sh reference with curl -fsSL from GitHub raw URL. The dynamic devfile now works when any project is cloned (not just the containerfile repo). Added retry logic (3 attempts, 5s backoff, 60s timeout) and graceful error handling — workspace starts even if tool install fails.
• Factory URL documentation: Added one-click workspace creation patterns for both devfile.yaml (default) and devfile-dynamic.yaml (explicit ?devfilePath=).
• Red Hat Dev Spaces notes: Documented expected compatibility (honestly: not yet tested), known differences (per-user namespaces, OpenShift OAuth, image registry), and link to Dev Spaces docs.

Review Council

• 5 Divisor agents invoked (adversary, architect, guard, sre, testing)
• Verdict: APPROVE WITH ADVISORIES
• Fixes applied: retry logic + error handling for curl downloads, trade-off comment for mutable URL
• Advisory: mutable main branch URL is a conscious design trade-off (D1) — bounded by container isolation

Files Changed

File	Changes
devfile-dynamic.yaml	Curl from GitHub + retry + error handling
README.md	+Factory URLs, +Red Hat Dev Spaces sections
openspec/changes/cde-docs/	Proposal, design, delta spec, tasks

Closes #5