refactor: rename Profile* types to Persistent* for semantic clarity

[chaizhenhua]

Context

After unifying shared state and profile state into a single mechanism (PR #81), the Profile* naming no longer reflects the actual role of these types:

Current Name	Actual Role	Proposed Name
ProfileStore (trait)	Raw async KV backend	StorageBackend
ProfileAccess (struct)	Typed read/write layer	PersistentStore
ProfileKey (trait)	Namespace definition	PersistentKey
ProfileOwner (enum)	Internal addressing	Keep (already internal)

Why

• ProfileAccess now serves both profile and shared state — the "Profile" prefix is misleading
• access as a noun is vague; store better describes a typed KV read/write interface
• Persistent* unifies the naming and contrasts naturally with State* (in-memory transient)

Scope

~15 non-test files reference these types. The rename is mechanical but touches multiple crates:

• awaken-contract (trait definitions + re-exports)
• awaken-runtime (ProfileAccess, ProfileKeyRegistry, PluginRegistrar)
• awaken-stores (FileStore, InMemoryStore implementations)
• awaken-ext-deferred-tools (caller)
• Documentation (ADR, book, reference)

Approach

1. Rename at source, re-export old names as deprecated type aliases for one release cycle
2. Update all internal usages
3. Remove deprecated aliases in next breaking release