feat(rmi): update execution protocol, public discovery docs, and linked dataset model

[n0531m]

Summary of Changes

1. Two-Tier Execution Strategy & Determinism Protocol

• Standardized execution strategy across API skills (api-analyticshub, api-geminidataanalytics, api-roads-v1, api-roadsselection, api-routes).
• Prioritizes deterministic Bash+JQ helper scripts (Tier 1) while offering grounded Discovery Document schema contracts for polyglot runtimes (Tier 2).

2. Public API Discovery Document Sourcing

• Added canonical public REST discovery endpoints in ## References for public Google Cloud and Google Maps Platform APIs.

3. Linked Dataset Model & Cleanups (rmi-sampledatasets)

• Removed redundant single-region boston_2026.md in favor of universal linked dataset documentation in SKILL.md and references/metrics.md.
• Updated analytical sample queries to be local timezone aware (America/New_York for Boston EDT commute peak analysis).
• Converted scripts/list_sample_datasets.sh to 100% pure POSIX Bash + JQ, removing Python dependency.

4. Bundle Manifest & Architectural Graphs

• Re-generated .bundle-manifest.json and bundle architectural diagrams.