Deprecated get_source_changelog removed; search gains category/collection filters

Minor Changes

• 0b1a45e: Remove the deprecated get_source_changelog tool from the local stdio MCP bridge. It was deprecated in 0.71.0 in favor of get_catalog_entry with the changelog_* params (include_changelog / changelog_path / changelog_offset / changelog_limit / changelog_tokens); calling get_source_changelog by name now returns MCP's standard unknown-tool error. The REST helper sourceChangelog() is unchanged — get_catalog_entry and the admin source changelog CLI command still use it.
• e7d50b4: releases search gains --category <slug> and --collection <slug> filters. --category scopes hits to organizations in a category (the API validates and resolves curator aliases like e-commerce → commerce, so the value is forwarded as-is); --collection scopes to a curated collection's member orgs (unknown slugs report "no collection matching …", mirroring --domain). Both forward to the new /v1/search params and compose with the existing --domain / --product / --kind / --since / --until scopes.
• 2d4b707: Surface the registry's AI-scored release importance (1–5, null when unscored). tail/latest gains --min-importance <1-5> (forwarded as ?minImportance=); the human table marks importance ≥4 with a quiet glyph (outline at 4, solid at 5), mirroring the web's render threshold, while --json output (get/tail/latest) passes the raw score through verbatim, including null. Bumps the @buildinternet/releases-api-types and @buildinternet/releases-core pins to the versions that carry the importance field.