docs: fix onboarding gaps from fable review of self-hosting stories (PROJ-367..372)

[TAJD]

Summary

Implements the projektor-deploy-example-side sub-issues of PROJ-365 (epic):

• PROJ-369 — corrected the forker instructions that told people to "point deploy.yml at your own wrangler.toml", which is gitignored by design (the exact bug PROJ-284 fixed for the demo).
• PROJ-367 — replaced the misleading PROJEKTOR_REPO=you/projektor placeholder with TAJD/projektor in AGENT-DEPLOY.md and CONFIGURE.md.
• PROJ-368 — fixed the nonexistent v1.0.0 example release tag in README.md; now points at gh release list + a real tag.
• PROJ-370 — added a one-click-specific branch to CONFIGURE.md step 2 for setting CF_ACCESS_TEAM_DOMAIN/CF_ACCESS_AUDIENCE without a local wrangler.toml.
• PROJ-371 — new CONTRIBUTING.md documenting the main-require-deploy-check ruleset and its known limitation (deploy-time failures only surface post-merge).
• PROJ-372 — linked the live demo near the top of README.md, reworded "builds + deploys" to "downloads + deploys" (no build step).

The projektor-repo-side sub-issues (PROJ-366, and the projektor.wt halves of PROJ-367/368/372) are in a companion PR: TAJD/projektor#93

Test plan

• Reviewed each diff manually for correctness (doc-only changes)
• Human review + merge; this repo's deploy.yml will run as a PR dry-run check
• Human review via the projektor issue tracker workflow (agent sessions can't self-transition issues to done)

🤖 Generated with Claude Code

https://claude.ai/code/session_01FG4F7B3e8xN4Fy5zzPUj2d