chore: adopt shared engineering standards

[lemarier]

Adopt the shared Origin89 engineering guidance through a task-start skill refresh. Each repository keeps its local constraints and checks; shared skills are downloaded into an ignored, verified cache instead of copied into version control.

Run the existing camera validation through just check locally and in CI. Lock Python dependencies with hashes, pin just, and retain the immutable fabrication export and camera-specific rules.

Validation:

• just check: the archived export still fails the existing C-02 mounting-hole copper keep-outs documented in Ground pour reaches all four mounting holes (C-02, C-03) #1. The check remains blocking; no rule or tolerance was weakened.
• Live skill refresh and verified offline cache pass; skill links and cache are ignored.
• actionlint, recipe parsing, and git diff --check pass.

Draft because the existing artwork gate is red. This change does not modify artwork or claim bench qualification.

[Copilot]

🟡 Changes recommended

CI will remain failing because just check continues to validate the pinned Gerber export that still violates the blocking C-02 keep-out rule described in #1.

Once you've addressed the issues Copilot identified, you can request another Copilot review.

Pull request overview

Adopts the shared Origin89 engineering guidance by adding a task-start skill refresh mechanism (cached and ignored), standardizing local developer/CI setup around just, and locking Python validation dependencies with hashes so the Gerber validation can run consistently in CI and locally.

Changes:

• Add just skills-sync bootstrap wiring plus local docs (AGENTS.md, CLAUDE.md, CONTRIBUTING.md) to align with shared engineering standards while keeping repo-specific constraints.
• Lock validation dependencies via requirements-dev.in → hash-pinned requirements-dev.txt, and update CI to install with --require-hashes.
• Route CI validation through just check (which runs the pinned Gerber validation against the committed export).

File summaries

File	Description
requirements-dev.txt	Adds a hash-locked dependency set for reproducible board validation installs.
requirements-dev.in	Defines the small, human-edited inputs for regenerating the locked requirements file.
justfile	Introduces skills-sync and standardizes validation entrypoints via just check.
CONTRIBUTING.md	Documents the new bootstrap flow, required tool versions, and dependency regen command.
CLAUDE.md	Points agents/tools at AGENTS.md as the primary task-start instructions.
AGENTS.md	Adds repo-local, task-start and board-work constraints aligned to shared standards.
.origin89/sync-engineering.py	Implements safe download/verification/caching of shared skills into an ignored local snapshot.
.gitignore	Ensures cached skills and local environment artifacts aren’t committed.
.github/workflows/check.yml	Updates CI to install pinned deps, set up just, and run just check.
.github/pull_request_template.md	Adds a structured PR template emphasizing validation evidence and completeness.

Review details

• Files reviewed: 9/10 changed files
• Comments generated: 0
• Review effort level: Lite

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