feat: resolve Oracle inline-view INSERT targets to their base table

[takaebato]

Summary

Implements a follow-up noted in #55: Oracle's inline-view INSERT
(INSERT INTO (SELECT … FROM emp) …) now resolves through to the view's single
base table as the write target, instead of dropping the whole statement as an
unsupported target. Semantically the row lands in the base table — the subquery
is an unnamed updatable view that restricts columns / enforces a predicate.

What resolves (single-table view only):

• Write target = the view's base table: INSERT INTO (SELECT a FROM emp) …
  writes emp (table level: create_tables=[emp]).
• Target columns = the view projection, as an explicit column list — plain
  columns only; a AS x writes base a. A wildcard / expression projection
  makes positions indeterminate → the usual column-less path (catalog fill, or
  InsertColumnsUnresolved). The explicit list also drives the arity check
  (… (SELECT a FROM emp) VALUES (1, 2) → InsertColumnsArityMismatch).
• View WHERE = filter reads against the target (what a WITH CHECK OPTION
  would enforce; sqlparser cannot parse the WITH CHECK OPTION keywords inside
  the target, so the plain predicate is what surfaces): reads emp.dept, never
  a lineage source. Carried on a new internal Insert::target_predicate.
• Column lineage traces through the view:
  INSERT INTO (SELECT a FROM emp) SELECT x FROM s → s.x → emp.a.

What stays flagged (UnsupportedStatement, as before): everything but the
minimal insertable-view shape (projection + FROM + WHERE). A join (Oracle's
key-preserved rules need a catalog), a set operation, a nested WITH / pipe
chain, or a non-table factor names no single base table — and any other clause
(GROUP BY / HAVING / DISTINCT / ORDER BY / FETCH / CONNECT BY / …) makes the
view non-insertable (ORA-01732) and could carry column refs that would
otherwise drop silently. Enforced by exhaustive Query / Select
destructures, so a new sqlparser clause forces a keep-or-reject decision.

Edge cases covered on review:

• An aliased base table (INSERT INTO (SELECT e.a FROM emp e WHERE e.dept = 10) …): the predicate's e.dept resolves through the alias to
  emp.dept (and, as in SQL, the alias shadows the bare table name).
• Clause-bearing views (GROUP BY / ORDER BY / DISTINCT / FETCH)
  previously slipped through the shape check with their column refs silently
  dropped — now rejected to the flag+drop path.
• INSERT OVERWRITE / REPLACE INTO bucketing (peel_to_insert) only reads
  the flags — unaffected.

TableReference's TryFrom<&Insert> sees through the same shapes (and errors
on the rest), so the public target-identity parse agrees with the analysis.

Tests: 7 column-level cases (values / WHERE-reads / lineage-through-view /
alias / wildcard / expression / arity), a table-level CRUD case, a
TryFrom<&Insert> unit test, and the existing subquery-target diagnostic test
narrowed to a join view. All gates green (fmt / clippy / test --all / doc).

Only OracleDialect parses this syntax (supports_insert_table_query).

🤖 Generated with Claude Code

[github-actions]

✅ PR title follows the Conventional Commits spec.

[codecov]

Codecov Report

❌ Patch coverage is 91.74312% with 9 lines in your changes missing coverage. Please review.
✅ Project coverage is 94.77%. Comparing base (9d76891) to head (aef20c2).

Files with missing lines	Patch %	Lines
sql-insight/src/reference.rs	88.52%	6 Missing and 1 partial ⚠️
sql-insight/src/resolver/binder/statement.rs	95.74%	2 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##           master      #58   +/-   ##
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  Coverage   94.77%   94.77%           
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  Files          27       27           
  Lines        5590     5686   +96     
  Branches     5590     5686   +96     
=======================================
+ Hits         5298     5389   +91     
- Misses        214      218    +4     
- Partials       78       79    +1     

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