feat: [GH-74] Temporal-range key-bracket binding (foo[t1...t2])

[javierlores]

Closes #74.

What

Extends the leaf key-bracket grammar so a key can bind to a half-open temporal interval [start, end) instead of a single instant, using the ... range separator. Three forms are supported on flat leaf keys:

Form	Meaning
foo[t1...t2]	closed range [t1, t2) (start-inclusive, end-exclusive)
foo[...t2]	open start — bounded on the end (exclusive)
foo[t1...]	open end — bounded on the start (inclusive)

This is grammar / AST / parse only. It defines the syntax, the AST node, and the canonical re-parseable string form. It does not decide what a range read returns — server-side evaluation (and the present-during vs. asserted-during choice) is a separate concourse change.

How

• Refactored BracketedTimestamp() into a raw-string KeyBracketParameter() and centralized single-instant vs. range interpretation in Parsing.applyKeyBracket, leaving the single-instant and navigation-stop paths unchanged.
• New TemporalRangeKeySymbol (sibling to TemporalKeySymbol): wraps a key plus optional start/end TimestampSymbols; rejects navigation and already-parameterized keys; requires at least one endpoint; rejects backwards ranges (start > end). isParameterized() is true, so writes and audit/chronicle/diff reject range bindings for free via the existing requireNotParameterized guard.
• The canonical toString() renders both endpoints as resolved microseconds (key[<m1>...<m2>]), making it a re-parseable cross-repo contract.

Parse-time validation

• foo[...] (both endpoints omitted) → rejected.
• foo[t2...t1] with t2 > t1 → rejected.
• foo[t1][t2...t3] (double bracket) → rejected.
• foo[t1...t2...t3] (more than one separator) → rejected. Separator detection is quote-aware, so a quoted phrase that itself contains ... is treated as a single endpoint rather than mis-split.

Tests

• Matrix (BracketTimestampMatrixTest): closed / open-start / open-end, quoted-date and natural-language endpoints, round-trip of resolved endpoints, and all rejection cases (fully-open, backwards, double-bracket, multiple-separator).
• Node (TemporalRangeKeySymbolTest): constructor guards, accessors, equals/hashCode, all three toString() shapes.
• Command (BracketTimestampCommandTest): range accepted on select/get/find; rejected on add and audit.

All parse-path and node tests pass locally, plus the existing GrammarTest / JavaCCParserTest / CompilerJavaCCTest suites (no regression). The parser regenerates cleanly from grammar.jjt.

Scope / follow-ups

• Out of scope: range bindings on navigation stops (a[t1...t2].b) and scope prefixes; server-side evaluation.
• Cross-repo dependency: concourse pins ccl 4.0.0. This must ship in a ccl release, after which concourse bumps its ccl pin before the matching range-evaluation change (cinchapi/concourse#789) can land — that change must teach Keys.parse to re-parse the canonical range toString() produced here.

Part of the connector data-sync locking initiative (cinchapi-server). Sibling grammar work: #75.