feat: catch-all router primitives + explore recipe skeleton

[HeinrichvH]

Enables a single "matcher": "*" entry in Claude Code's settings.json to route every tool call through Exactor, with per-rule intercept/skip logic living in .exactor.yml instead of duplicated across Claude config and Exactor config. Richer rule primitives + hard fail-open contract so catch-all doesn't turn a config typo into a session-wide block.

Fail-open contract

Under a catch-all matcher, any unexpected error in this hook blocks every tool call. pre_tool_use / post_tool_use now wrap their bodies in an outer try/except — on any exception (malformed stdin, missing worker, YAML parse error, runtime surprise) they log to stderr and exit 0 so the raw tool runs. Also validates route_to against defined workers at config-load time so misconfigs surface via exactor check rather than at tool-fire time. Runtime re-checks worker existence as belt-and-braces. Six new tests pin the contract: unmatched tool, missing config, malformed stdin, malformed YAML, load-time validation, runtime ghost-worker.

query_template

New InterceptRule.query_template field — Python str.format-style template that interpolates multiple tool_input fields into one query. Lets Grep intercepts fold pattern + path + glob into a natural-language question for a code-exploration subagent, instead of losing scope by picking just one field. Missing keys render as empty string via a SafeDict so optional fields don't raise. Takes precedence over query_field when both are set.

unless_match

New InterceptRule.unless_match field — regex on the templated query; rule is skipped if it matches. Symmetric with existing match, more flexible than the named unless predicates for query-shape heuristics (e.g. "skip trivially short patterns"). Both named unless and unless_match can coexist on the same rule.

CLI default subcommand

exactor hook (no subcommand) now defaults to event=pre. Older docs suggested the bare form, and a catch-all matcher exposes argparse failures as blocking hook errors on every tool call. Explicit forms (exactor hook pre, exactor hook post) continue to work unchanged.

recipes/explore/

Skeleton recipe documenting the shape for routing Grep / Glob (and optionally Read) to a code-search subagent. Ships with commented intercept rules, sensible defaults (cache: false — code changes under us), and a README explaining the contract (explore CLI takes one positional query arg, prints a cited report to stdout). Users bring their own subagent (Goose, Aider, Claude API, etc.).

Tests

57 passing, +14 new (fail-open x6, query_template x5, unless_match x2, cli-default x1).