docs: prepare Container Pilot RC12 for public testing

[DeepZone]

Summary

Prepares the public repository for external RC12 testing without changing application behavior.

• No runtime functionality changed.
• No version changed and no RC, tag, release, or image was created.
• No telemetry logic changed.
• No tracker code or deployment changed.

README cleanup

• Removes stale RC11 screenshot wording and corrects the immutable release-tag example.
• Keeps the authentic anonymized product screenshot early in both READMEs.
• Aligns English and German registry information and adds clear testing, Issues, and Discussions calls to action.

Project website

• Refreshes the static GitHub Pages landing page around Detect → Decide → Update → Verify → Recover.
• Adds the authentic anonymized product screenshot to the deployed site/assets tree.
• Covers Watchtower migration, opt-in telemetry, the Docker-socket security boundary, rollback limits, and a complete short quickstart.
• Adds canonical and Open Graph metadata without external scripts, fonts, analytics, or trackers.

Repository metadata

• Sets the repository homepage to https://deepzone.github.io/container-pilot/.
• Verifies the existing description, focused topics, MIT license, Pages, Issues, and Discussions settings; no unrelated metadata was changed.

RC testing readiness

• Expands the generic testing matrix for AMD64, ARM64, healthcheck and no-healthcheck containers, storage, networking, private registries, Watchtower migration, self-update, rollback, reverse proxies, and native HTTPS.
• Makes bug and RC feedback forms collect platform and reproduction details separately and strengthens privacy guidance.

Roadmap

• Makes real-world validation—not additional feature scope—the primary v1.0 gate.
• Adds field-validation and critical reliability/security exit criteria while leaving v1.1, v1.2, and future features in place.

Community / Discussions

• Created Container Pilot 0.9.0 RC12 - Testing & Feedback in General.
• Links testers directly to the testing guide and issue chooser.

Validation

• npm test — 45 passed, 2 expected integration skips, 0 failed
• JavaScript syntax checks — passed
• GitHub YAML parse checks — passed
• Local Markdown link validation — passed across 20 files
• git diff --check — passed
• Changed-file scan found no private IPs, internal credentials, passwords, keys, or host data
• Static page uses no external scripts, fonts, analytics, or trackers

Manual follow-up

• After merge, confirm the Pages deployment workflow succeeds on main and visually verify the published page at https://deepzone.github.io/container-pilot/.