fix(lint): respect module headers in declaration guard

[vicmcorrea]

bend-lint refuses safe formatting when a valid module-import header is indented. Its declaration guard also removes import-looking lines throughout the file, so it can miss changes inside multiline strings or reject unchanged foreign-function bodies.

Limit masking to the initial module-import header, following book_load's whitespace, comment and boundary rules. Recover fallback aliases from that same header while preserving parser-observed aliases. This adapts the standalone bend-lint correction to the bundled tool. Tests stay in bend-lint's suite, following the maintainer guidance in #1389.

Blast radius

• The production change is confined to sameDeclarations in tools/bend-lint/src/seam.ts. It affects rules that use this guard, including the formatter's safety check.
• Only initial import Base and import path as Alias header lines are masked. Scanning stops at the first body line, including @unsafe. Foreign imports, later imports and multiline literal contents remain part of the comparison.
• The guard still compares parsed declarations using the already checked imports. Module loading, compiler/checker code and formatting rules are unchanged. The other changed file contains seven regressions in rules/format.test.ts.

Validation

• bun test from tools/bend-lint passes all 122 tests. Each of the seven new regressions fails against the original guard.
• Actual CLI checks cover LF/CRLF, indented Base and module imports, foreign imports, and imported-law proofs. Safe fixes match the expected text, a second lint is clean, and tested source/emitted-JS output remains 7.
• bun gates/repo.ts passes 54/54. git diff --check passes.

Validation limits

Typecheck still reports the same two pre-existing TS2339 errors in bend2/bend.ts, at lines 2040 and 3771. The before/after diagnostics are identical. These checks cover the bundled linter and tested programs; full cluster gates were not run.