docs: document storage in language-specific READMEs

[ikenyal]

Issue #, if available

N/A. This documents the existing storage component added in #28 and the Python default search behavior fixed in #42.

Description of changes

The root README lists Storage as an extension point, but the Python and TypeScript READMEs omit it from their component tables, implementation guidance, and naming conventions.

This change adds those missing entries in both language READMEs. It describes the four asynchronous persistence methods, raw-byte values, missing-key behavior, and prefix listing. The Python guidance covers inherited keyword search; the TypeScript guidance covers backend configuration and distinguishes raw-byte Storage from SnapshotStorage.

Documentation only; no SDK behavior, template source, setup scripts, or dependencies change.

Testing

Verified locally on macOS arm64 with Python 3.12.12 and Node.js 22.22.2:

• Existing Python template: 12 tests pass; Ruff formatting/lint and mypy pass.
• Existing TypeScript template: npm run check passes, including all 11 tests, formatting, lint, and type checks.
• Generated storage-only projects for both languages, using both default hoisting and retained-monorepo layouts. Confirmed the README entries survive setup and TypeScript configuration names are renamed correctly.
• Generated Python projects: all 4 tests pass in each layout; Ruff formatting/lint and mypy pass.
• Generated TypeScript projects: npm install --ignore-scripts, npm run check (1 test), and npm run build pass in each layout.
• git diff --check passes.

Setup was exercised only in disposable local copies. No model calls, AWS resources, or GPU were used. Linux and Windows were not executed locally.

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