refactor(seccomp): extract trusted policy substrate

[RaresKeY]

Summary

This draft extracts the trusted seccomp substrate from the cumulative sandbox work in #5818 into an independently reviewable change. It adds deterministic Moby-derived policy generation with pinned provenance, generated inner and outer artifacts, the hardened fixed Bubblewrap launcher, and focused generator, policy, and launcher tests. Dockerfile, Compose, AppArmor, boot self-test, and process-routing integration remain outside this slice.

The scope is exactly these 12 paths:

• docker/seccomp/odysseus-bubblewrap.json
• security/seccomp/Makefile
• security/seccomp/README.md
• security/seccomp/generate.py
• security/seccomp/generated_inner_policy.h
• security/seccomp/moby-default.json
• security/seccomp/odysseus-seccomp-launcher.c
• security/seccomp/policy.json
• tests/seccomp_probe.c
• tests/test_seccomp_generator.py
• tests/test_seccomp_launcher.py
• tests/test_seccomp_policy.py

The generated outer profile docker/seccomp/odysseus-bubblewrap.json is canonically owned by this PR. PR #6121 consumes this generated profile for Docker/Compose integration and must not duplicate or regenerate it.

Target branch

• This PR targets dev, not main. All PRs land in dev; main is curated by the maintainer at each release. If your PR is on main by accident, click "Edit" on this PR and change the base.

Linked Issue

Fixes #6114

Part of #6091

Part of #5815

Related to #5818; this supersedes the corresponding seccomp-substrate slice of that cumulative PR.

Related to #4754, the broader sandbox request.

Type of Change

• Bug fix (non-breaking — fixes a confirmed issue)
• New feature (non-breaking — adds new behaviour)
• Breaking change (changes or removes existing behaviour)
• Refactor / cleanup (behaviour unchanged)
• Documentation only
• CI / tooling / configuration

Checklist

• I searched open issues and open PRs — this is not a duplicate.
• This PR targets dev
• My changes are limited to the scope described above — no unrelated refactors or whitespace changes mixed in.
• I actually ran the app (docker compose up or uvicorn app:app) and verified the change works end-to-end. Type-checks and unit tests are not enough.
• I did not run the app/runtime validation and stated that gap in How to Test. Leave this unchecked when the app-run box above is checked.

How to Test

All commands below were run in a secretless review environment against this exact 12-path branch.

1. Run python3 security/seccomp/generate.py --check --verify-arches to verify pinned Moby provenance, deterministic generated artifacts, and x86_64/ARM64 resolution; it passed.
2. Run make -C security/seccomp check-generated; it passed. Run python3 -m py_compile security/seccomp/generate.py; it passed.
3. Run python3 -m pytest -q tests/test_seccomp_generator.py tests/test_seccomp_policy.py; 7 tests passed. Run python3 -m pytest -q tests/test_seccomp_launcher.py; 16 tests passed.
4. Full app, Docker/Compose, AppArmor, boot self-test, and browser validation were not run here; those host-integration checks remain outside this focused substrate PR and should be covered by the corresponding follow-up slice.

Visual / UI changes — REQUIRED if you touched anything that renders

Anything that changes what the UI looks like — buttons, icons, padding, colors, fonts, spacing, layout, CSS, HTML, SVG, or any static/js/ module that draws to the DOM — needs all of the following. PRs that change rendering without these WILL be closed.

This slice does not touch UI-rendering files.

• Screenshot or short clip of the change in the running app, attached below.
• Style match: the change uses Odysseus's existing visual language. Specifically:
  • Reuse existing CSS variables (--red, --fg, --bg, --card, --border, etc.) — do not introduce new color values, font sizes, or spacing units.
  • Reuse existing button/input/card/border classes. Don't invent parallel styling.
  • No Unicode emoji in UI or code. Use inline SVG (matching the monochrome icon style already in static/index.html) or plain text.
  • Monospaced font (Fira Code) for primary UI text. Don't override.
  • Dark theme is the default; any light-mode work must be wired through the existing theme system, not hard-coded.
• No new component patterns. If a similar widget already exists in the app, extend it instead of writing a parallel one.
• I am not an LLM agent submitting a bulk PR. If you are, please open an issue describing the problem first — bulk auto-generated PRs that don't match the project's visual style are closed on sight, even when the underlying code is correct.

Screenshots / clips

[github-actions]

⚠️ PR description is complete; validation evidence is still outstanding

Changed-file classification: backend/runtime.

Author-reported runtime / visual state

• The author explicitly reports that app/runtime validation was not performed.

Checkboxes are author attestations. GitHub Actions results remain the execution evidence for CI; this check does not prove that a local command ran.

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