feat: add persistent fingerprint seeds

[PopcornDev1]

Summary

Adds an optional fingerprint_seed parameter for Camoufox-generated
fingerprints so callers can reproduce stable generated identity values across
launches and browser contexts.

Related issues/discussions:

• Addresses Deterministic Hardware Fingerprinting (Seed Persistence) for Session Reuse #442
• Addresses Persistent fingerprint #38
• Addresses when persistent_context=True,restarting the browser,the fingerprint is changed #71
• Addresses Inconsistent Fingerprint IDs on Multiple Camoufox Runs with Same Args on creepjs #328
• Addresses Expand support to account for all properties of the fingerprint parameter #378
• Related to discussions How to make truly persistent contexts? #263, persistent context == saving browser fp? #373, Exporting a fingerprint #151, and Disable fingerprinting #255

This is intentionally Python/API-level only. It does not include browser engine,
C++, TLS, networking, or renderer-level fingerprinting changes.

Motivation

Camoufox is good at generating fresh fingerprints, but persistent profiles need
a way to keep generated fingerprint values stable across restarts. Several users
have reported that cookies/storage can persist while generated fingerprint
surfaces still rotate, causing CreepJS/fingerprint IDs or browser identity
signals to change between runs.

fingerprint_seed gives callers a stable generation input while preserving the
current random-by-default behavior when no seed is supplied.

What Changed

• Added deterministic seed derivation helpers in pythonlib/camoufox/ & fingerprint_seed.py.
• Added optional fingerprint_seed support to:
  • launch_options()
  • sync NewContext()
  • async AsyncNewContext()
  • generate_context_fingerprint()
  • BrowserForge generation/conversion
  • WebGL sampling
• Supports str, int, and bytes seeds.
• Rejects unsupported seed types such as bool.
• Uses versioned, length-prefixed SHA-256 material to derive independent
  namespace-specific sub-seeds.
• Keeps unseeded behavior random.
• Ensures fingerprint_seed is consumed by Camoufox and not forwarded to
  Playwright.
• Avoids unsupported context-level canvas setter calls in generated init
  scripts.
• Adds a macOS .app bundle fallback for locating properties.json.

Seeded Surfaces

Seeded generation now covers Camoufox-owned generated values including:

• BrowserForge sampling
• preset selection
• OS choice where applicable
• WebGL sampling
• font and voice subsets
• screen offset sampling
• window.history.length
• audio/canvas/font spacing config seeds

Compatibility / Caveats

• Existing callers are unaffected unless they pass fingerprint_seed.
• fingerprint_seed controls generated fingerprint values only.
• It does not persist cookies, local storage, cache, or browser profile state.
• Persistent state should still use a stable user_data_dir / persistent
  context.
• Context-level seeds apply only to surfaces exposed by the current per-context
  init-script path.
• This PR does not change TLS, proxy, network, or renderer-level behavior.

Testing

Regression tests added for:

• deterministic seed derivation
• namespace/type separation
• invalid seed input handling
• sync and async context API forwarding
• deterministic launch config generation
• deterministic context fingerprint generation
• different seeds producing different noise values
• unseeded launch/context paths remaining randomized
• BrowserForge stability with concurrent seeded and unseeded calls
• macOS app bundle properties.json fallback

Local checks run:

PYTHONDONTWRITEBYTECODE=1 PYTHONPATH=pythonlib python3 -m pytest
--confcutdir=tests/patches tests/patches/fingerprint-seed.py tests/patches/
context-api-seed.py tests/patches/context-fingerprint-seed.py tests/patches/
launch-options-seed.py tests/patches/live-fingerprint-seed.py

Result:

18 passed, 2 skipped

Dogfooding

This branch is being dogfooded in VulpineOS for long-lived agent identities:

• stable profile/account identifier -> fingerprint_seed
• stable browser profile directory -> user_data_dir
• generated Camoufox fingerprint values stay reproducible across restarts
• cookies/storage/profile state remain handled separately by the persistent
  profile layer

[PopcornDev1]

@icepaq