Add native personal agent history providers

[luca-ctx]

Summary

• add first-class native history providers for OpenClaw, Hermes Agent, NanoClaw, and AstrBot
• wire provider IDs, CLI aliases, source discovery, import dispatch, provider filters, search refresh boundaries, store provider constraints, and support-matrix docs
• mark Hermes as imported/GA-style SQLite support, OpenClaw as beta/partial JSONL support, and NanoClaw/AstrBot as preview explicit-import sources excluded from import-all and pre-search refresh
• preserve source paths/cursors and add CLI coverage for sources, import, search, show/locate provenance, idempotency, incremental imports, corrupt DBs, and preview boundaries

Fidelity Notes

• OpenClaw reads session JSONL under OPENCLAW_STATE_DIR, ~/.openclaw, and legacy .clawdbot/.moltbot; support remains beta because upstream storage accessors are still evolving.
• Hermes reads state.db read-only and preserves sessions/messages, parent IDs, model/config, tool metadata, token fields, and billing metadata when present.
• NanoClaw preview reads project-local data/v2.db plus per-session inbound/outbound DBs; it is explicit-import only until more project layout drift is validated.
• AstrBot preview reads data/data_v4.db conversation context plus available platform_message_history; it does not claim complete all-channel IM transcript fidelity.

Review Follow-ups Addressed

• fixed v15 provider-check migration to disable/restore foreign keys and recreate indexes while rebuilding referenced tables
• made NanoClaw event identity include row IDs so duplicate same-direction seq values do not collide
• tolerated partial NanoClaw auxiliary table schemas
• made OpenClaw explicit single-file JSONL imports consistent with source/import behavior
• removed misleading unsupported_reason from importable preview source rows and aligned docs with provider-only explicit preview imports

Tests

• scripts/check-docs.sh
• cargo check -p ctx-history-capture -p ctx-history-store -p ctx-history-core -p ctx
• cargo test -p ctx --test cli -- --nocapture
• cargo test -p ctx-history-store schema_v15_rebuilds_provider_checks_with_referenced_sources_and_indexes -- --nocapture
• cargo test -p ctx-history-capture provider_sources -- --nocapture
• cargo test --workspace -- --nocapture