fix: make PromptSyntax explicit and add the experimental profile

[pathscale]

Summary

• make authored PromptSyntax directives resolve visibly instead of falling through as literal transcript text
• preserve PromptSyntax outcomes and working-directory permission behavior across project runs
• add an AgencyZero Experimental app identity, updater channel, release workflow, and direct pinned agent-experimental dependency behind the experimental feature
• apply the expanded Codex context policy to GPT-5.6 Sol runs and checkpoints, with a conservative 340k compaction guard in the dependency
• store the Claude OAuth token in macOS Keychain and show subscription usage at the bottom of Experimental settings
• remove AWS-LC and avoid OpenSSL in the macOS dependency tree by using rustls with ring
• share macOS release caches, reduce CI debug information, and remove the redundant workspace build
• inventory ORG2, RTK, and Ponytail token optimization candidates
• bump the combined release to 0.1.58 in an isolated final commit

This PR now contains and supersedes #77.

Verification

• frontend typecheck, lint, and 266 tests
• cargo fmt, strict all-target all-feature clippy, and full workspace tests including 101 GUI tests
• standard Tauri release link
• experimental Tauri release link
• macOS resolved dependency tree contains no OpenSSL, native-tls, or AWS-LC
• live ChatGPT-authenticated context matrix for Sol, Terra, and Luna: all completed and cold-resumed above the stock 258.4k window; the common observed route ceiling is about 371k

Release

The standard and experimental workflows use separate concurrency groups and can build in parallel. The experimental updater publishes under its own CDN directory. The companion Homebrew cask is proposed in pathscale/homebrew-tap#1.