fix source routing for import and search

[tyad67-netizen]

Summary

Fixes two source-routing bugs:

• gbrain import --source <id> now routes imported pages/chunks to the requested source using the existing resolveSourceId chain.
• gbrain search --source <id> now applies a source filter in both PGLite and Postgres keyword search paths.

Also:

• Preserves programmatic opts.sourceId compatibility.
• Guards missing --source values.
• Updates CLI/docs help text.
• Adds regression coverage for source-filtered keyword search.

Fixes #1167.

Test Plan

Local focused verification:

./bin/bun run typecheck
PATH="$PWD/bin:$PATH" ./bin/bun test test/source-id-tx-regression.test.ts test/build-llms.test.ts
# 27 pass / 0 fail
PATH="$PWD/bin:$PATH" ./bin/bun run build

Manual end-to-end smoke:

• isolated temp GBRAIN_HOME
• create sources alpha, beta
• import vault A with --source alpha
• import vault B with --source beta
• verify search --source alpha only returns alpha
• verify search --source beta only returns beta
• verify search --source default does not return imported alpha/beta hits
• verify missing --source value fails loudly

Real acceptance verification against local HermesClaude vault:

default               federated          0 pages
hermes-local-wiki     isolated           0 pages
hermesclaude-main     federated        567 pages
hermesintake          isolated           0 pages
openclaw-wiki         isolated           0 pages

Search query HermesClaude:

• --source hermesclaude-main: returns hits
• --source hermesintake: No results
• --source openclaw-wiki: No results
• --source default: No results
• --source __all__: returns hits

[garrytan]

Closing in favor of #1253 (v0.37.7.0 fix wave) which re-implements source routing for gbrain import, gbrain extract, and gbrain query against current master.

Specifically your work informed the --source-id flag shape on import.ts; the v0.37.7.0 implementation lives at src/commands/import.ts with a regression test at test/import-source-id.test.ts.

Per the wave's "re-implement, credit, close" workflow, your contribution is acknowledged via Co-Authored-By: tyad67-netizen trailer in the import-source-id commit. Thank you for the fix and the time on this.